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TCSH(1)                                                                                              TCSH(1)

       tcsh - C shell with file name completion and command line editing

       tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg ...]
       tcsh -l

       tcsh  is an enhanced but completely compatible version of the Berkeley UNIX C shell, csh(1).  It is a
       command language interpreter usable both as an interactive login shell and  a  shell  script  command
       processor.   It  includes a command-line editor (see The command-line editor), programmable word com-pletion completion
       pletion (see Completion and listing), spelling correction (see Spelling correction), a history mecha-nism mechanism
       nism  (see  History substitution), job control (see Jobs) and a C-like syntax.  The NEW FEATURES sec-tion section
       tion describes major enhancements of tcsh over csh(1).  Throughout this manual, features of tcsh  not
       found  in most csh(1) implementations (specifically, the 4.4BSD csh) are labeled with `(+)', and fea-tures features
       tures which are present in csh(1) but not usually documented are labeled with `(u)'.

   Argument list processing
       If the first argument (argument 0) to the shell is `-' then it is a login shell.  A login  shell  can
       be also specified by invoking the shell with the -l flag as the only argument.

       The rest of the flag arguments are interpreted as follows:

       -b  Forces  a  ``break'' from option processing, causing any further shell arguments to be treated as
           non-option arguments.  The remaining arguments will not be interpreted as  shell  options.   This
           may  be  used  to  pass  options to a shell script without confusion or possible subterfuge.  The
           shell will not run a set-user ID script without this option.

       -c  Commands are read from the following argument (which must be present, and must be a single  argu-ment), argument),
           ment), stored in the command shell variable for reference, and executed.  Any remaining arguments
           are placed in the argv shell variable.

       -d  The shell loads the directory stack from ~/.cshdirs as  described  under  Startup  and  shutdown,
           whether or not it is a login shell. (+)

           Sets the environment variable name to value. (Domain/OS only) (+)

       -e  The shell exits if any invoked command terminates abnormally or yields a non-zero exit status.

       -f  The  shell  does not load any resource or startup files, or perform any command hashing, and thus
           starts faster.

       -F  The shell uses fork(2) instead of vfork(2) to spawn processes. (+)

       -i  The shell is interactive and prompts for its top-level input, even if it appears to not be a ter-minal. terminal.
           minal.  Shells are interactive without this option if their inputs and outputs are terminals.

       -l  The shell is a login shell.  Applicable only if -l is the only flag specified.

       -m  The  shell  loads  ~/.tcshrc even if it does not belong to the effective user.  Newer versions of
           su(1) can pass -m to the shell. (+)

       -n  The shell parses commands but does not execute them.  This aids in debugging shell scripts.

       -q  The shell accepts SIGQUIT (see Signal handling) and behaves when it is  used  under  a  debugger.
           Job control is disabled. (u)

       -s  Command input is taken from the standard input.

       -t  The  shell reads and executes a single line of input.  A `\' may be used to escape the newline at
           the end of this line and continue onto another line.

       -v  Sets the verbose shell variable, so that command input is echoed after history substitution.

       -x  Sets the echo shell variable, so that commands are echoed immediately before execution.

       -V  Sets the verbose shell variable even before executing ~/.tcshrc.

       -X  Is to -x as -V is to -v.

           Print a help message on the standard output and exit. (+)

           Print the version/platform/compilation options on the standard output and exit.  This information
           is also contained in the version shell variable. (+)

       After  processing  of  flag  arguments, if arguments remain but none of the -c, -i, -s, or -t options
       were given, the first argument is taken as the name of a file of commands, or ``script'', to be  exe-cuted. executed.
       cuted.   The  shell  opens this file and saves its name for possible resubstitution by `$0'.  Because
       many systems use either the standard version 6 or version 7 shells whose shell scripts are  not  com-patible compatible
       patible with this shell, the shell uses such a `standard' shell to execute a script whose first char-acter character
       acter is not a `#', i.e., that does not start with a comment.

       Remaining arguments are placed in the argv shell variable.

   Startup and shutdown
       A login shell begins by executing commands from the system files /etc/csh.cshrc  and  /etc/csh.login.
       It  then  executes  commands  from  files  in  the  user's home directory: first ~/.tcshrc (+) or, if
       ~/.tcshrc is not found, ~/.cshrc, then ~/.history (or the value of the histfile shell variable), then
       ~/.login,  and  finally  ~/.cshdirs (or the value of the dirsfile shell variable) (+).  The shell may
       read /etc/csh.login before instead of after /etc/csh.cshrc, and  ~/.login  before  instead  of  after
       ~/.tcshrc or ~/.cshrc and ~/.history, if so compiled; see the version shell variable. (+)

       Non-login shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on startup.

       For examples of startup files, please consult

       Commands  like  stty(1)  and  tset(1),  which  need  be  run only once per login, usually go in one's
       ~/.login file.  Users who need to use the same set of files with both csh(1) and tcsh can have only a
       ~/.cshrc  which checks for the existence of the tcsh shell variable (q.v.) before using tcsh-specific
       commands, or can have both a ~/.cshrc and  a  ~/.tcshrc  which  sources  (see  the  builtin  command)
       ~/.cshrc.  The rest of this manual uses `~/.tcshrc' to mean `~/.tcshrc or, if ~/.tcshrc is not found,

       In the normal case, the shell begins reading commands from the terminal, prompting with `> '.   (Pro-cessing (Processing
       cessing  of  arguments  and  the  use  of  the  shell to process files containing command scripts are
       described later.)  The shell repeatedly reads a line of command input, breaks it into  words,  places
       it on the command history list, parses it and executes each command in the line.

       One  can  log  out by typing `^D' on an empty line, `logout' or `login' or via the shell's autologout
       mechanism (see the autologout shell variable).  When a login shell  terminates  it  sets  the  logout
       shell  variable  to  `normal'  or  `automatic'  as appropriate, then executes commands from the files
       /etc/csh.logout and ~/.logout.  The shell may drop DTR on logout if  so  compiled;  see  the  version
       shell variable.

       The names of the system login and logout files vary from system to system for compatibility with dif-ferent different
       ferent csh(1) variants; see FILES.

       We first describe The command-line editor.  The Completion and listing and Spelling  correction  sec-tions sections
       tions  describe  two  sets of functionality that are implemented as editor commands but which deserve
       their own treatment.  Finally, Editor commands lists and describes the editor  commands  specific  to
       the shell and their default bindings.

   The command-line editor (+)
       Command-line input can be edited using key sequences much like those used in GNU Emacs or vi(1).  The
       editor is active only when the edit shell variable is set, which it  is  by  default  in  interactive
       shells.   The bindkey builtin can display and change key bindings.  Emacs-style key bindings are used
       by default (unless the shell was compiled otherwise; see the version shell variable), but bindkey can
       change the key bindings to vi-style bindings en masse.

       The shell always binds the arrow keys (as defined in the TERMCAP environment variable) to

           down    down-history
           up      up-history
           left    backward-char
           right   forward-char

       unless  doing  so  would  alter  another  single-character binding.  One can set the arrow key escape
       sequences to the empty string with settc to prevent these bindings.   The  ANSI/VT100  sequences  for
       arrow keys are always bound.

       Other  key bindings are, for the most part, what Emacs and vi(1) users would expect and can easily be
       displayed by bindkey, so there is no need to list them here.  Likewise, bindkey can list  the  editor
       commands with a short description of each.

       Note  that  editor  commands do not have the same notion of a ``word'' as does the shell.  The editor
       delimits words with any non-alphanumeric characters not in the shell variable  wordchars,  while  the
       shell recognizes only whitespace and some of the characters with special meanings to it, listed under
       Lexical structure.

   Completion and listing (+)
       The shell is often able to complete words when given a unique abbreviation.  Type part of a word (for
       example  `ls /usr/lost') and hit the tab key to run the complete-word editor command.  The shell com-pletes completes
       pletes the filename `/usr/lost' to `/usr/lost+found/', replacing the incomplete word  with  the  com-plete complete
       plete  word  in  the  input buffer.  (Note the terminal `/'; completion adds a `/' to the end of com-pleted completed
       pleted directories and a space to the end of other completed words, to speed  typing  and  provide  a
       visual  indicator  of  successful  completion.   The addsuffix shell variable can be unset to prevent
       this.)  If no match is found (perhaps `/usr/lost+found' doesn't exist), the terminal bell rings.   If
       the  word  is  already  complete  (perhaps there is a `/usr/lost' on your system, or perhaps you were
       thinking too far ahead and typed the whole thing) a `/' or space is added to  the  end  if  it  isn't
       already there.

       Completion  works  anywhere  in  the line, not at just the end; completed text pushes the rest of the
       line to the right.  Completion in the middle of a word often results in leftover  characters  to  the
       right of the cursor that need to be deleted.

       Commands  and  variables  can be completed in much the same way.  For example, typing `em[tab]' would
       complete `em' to `emacs' if emacs were the only command on your system beginning with `em'.   Comple-tion Completion
       tion can find a command in any directory in path or if given a full pathname.  Typing `echo $ar[tab]'
       would complete `$ar' to `$argv' if no other variable began with `ar'.

       The shell parses the input buffer to determine whether the word you want to complete should  be  com-pleted completed
       pleted as a filename, command or variable.  The first word in the buffer and the first word following
       `;', `|', `|&', `&&' or `||' is considered to be a command.  A word beginning with `$' is  considered
       to be a variable.  Anything else is a filename.  An empty line is `completed' as a filename.

       You can list the possible completions of a word at any time by typing `^D' to run the delete-char-or-list-or-eof delete-char-orlist-or-eof
       list-or-eof editor command.  The shell lists the possible completions using the ls-F  builtin  (q.v.)
       and reprints the prompt and unfinished command line, for example:

           > ls /usr/l[^D]
           lbin/       lib/        local/      lost+found/
           > ls /usr/l

       If  the  autolist shell variable is set, the shell lists the remaining choices (if any) whenever com-pletion completion
       pletion fails:

           > set autolist
           > nm /usr/lib/libt[tab]
           libtermcap.a@ libtermlib.a@
           > nm /usr/lib/libterm

       If autolist is set to `ambiguous', choices are listed only when completion  fails  and  adds  no  new
       characters to the word being completed.

       A  filename  to  be completed can contain variables, your own or others' home directories abbreviated
       with `~' (see Filename substitution) and directory stack entries abbreviated with `=' (see  Directory
       stack substitution).  For example,

           > ls ~k[^D]
           kahn    kas     kellogg
           > ls ~ke[tab]
           > ls ~kellogg/


           > set local = /usr/local
           > ls $lo[tab]
           > ls $local/[^D]
           bin/ etc/ lib/ man/ src/
           > ls $local/

       Note that variables can also be expanded explicitly with the expand-variables editor command.

       delete-char-or-list-or-eof  lists at only the end of the line; in the middle of a line it deletes the
       character under the cursor and on an empty line it logs one out or, if ignoreeof is set,  does  noth-ing. nothing.
       ing.   `M-^D', bound to the editor command list-choices, lists completion possibilities anywhere on a
       line, and list-choices (or any one of the related editor commands  that  do  or  don't  delete,  list
       and/or  log  out,  listed  under  delete-char-or-list-or-eof)  can  be bound to `^D' with the bindkey
       builtin command if so desired.

       The complete-word-fwd and complete-word-back editor commands (not bound to any keys by  default)  can
       be  used  to  cycle  up and down through the list of possible completions, replacing the current word
       with the next or previous word in the list.

       The shell variable fignore can be set to a list of suffixes to be ignored  by  completion.   Consider
       the following:

           > ls
           Makefile        condiments.h~   main.o          side.c
           README          main.c          meal            side.o
           condiments.h    main.c~
           > set fignore = (.o \~)
           > emacs ma[^D]
           main.c   main.c~  main.o
           > emacs ma[tab]
           > emacs main.c

       `main.c~'  and  `main.o' are ignored by completion (but not listing), because they end in suffixes in
       fignore.  Note that a `\' was needed in front of `~' to prevent it from being  expanded  to  home  as
       described under Filename substitution.  fignore is ignored if only one completion is possible.

       If the complete shell variable is set to `enhance', completion 1) ignores case and 2) considers peri-ods, periods,
       ods, hyphens and underscores (`.', `-' and `_') to be word separators and hyphens and underscores  to
       be equivalent.  If you had the following files

           comp.lang.c      comp.lang.perl   comp.std.c++
           comp.lang.c++    comp.std.c

       and  typed  `mail  -f  c.l.c[tab]', it would be completed to `mail -f comp.lang.c', and ^D would list
       `comp.lang.c'  and  `comp.lang.c++'.   `mail  -f   c..c++[^D]'   would   list   `comp.lang.c++'   and
       `comp.std.c++'.  Typing `rm a--file[^D]' in the following directory

           A_silly_file    a-hyphenated-file    another_silly_file

       would  list  all  three  files,  because  case is ignored and hyphens and underscores are equivalent.
       Periods, however, are not equivalent to hyphens or underscores.

       Completion and listing are affected by several other shell variables: recexact can be set to complete
       on the shortest possible unique match, even if more typing might result in a longer match:

           > ls
           fodder   foo      food     foonly
           > set recexact
           > rm fo[tab]

       just beeps, because `fo' could expand to `fod' or `foo', but if we type another `o',

           > rm foo[tab]
           > rm foo

       the completion completes on `foo', even though `food' and `foonly' also match.  autoexpand can be set
       to run the expand-history editor command before each completion attempt, autocorrect can  be  set  to
       spelling-correct  the  word  to be completed (see Spelling correction) before each completion attempt
       and correct can be set to complete commands automatically after one hits `return'.  matchbeep can  be
       set  to  make  completion beep or not beep in a variety of situations, and nobeep can be set to never
       beep at all.  nostat can be set to a list of directories and/or patterns that  match  directories  to
       prevent  the  completion mechanism from stat(2)ing those directories.  listmax and listmaxrows can be
       set to limit the number of items and rows (respectively) that are listed without asking first.   rec-ognize_only_executables recognize_only_executables
       ognize_only_executables can be set to make the shell list only executables when listing commands, but
       it is quite slow.

       Finally, the complete builtin command can be used to tell the shell how to complete words other  than
       filenames, commands and variables.  Completion and listing do not work on glob-patterns (see Filename
       substitution), but the list-glob and expand-glob editor commands  perform  equivalent  functions  for

   Spelling correction (+)
       The  shell  can  sometimes  correct the spelling of filenames, commands and variable names as well as
       completing and listing them.

       Individual words can be spelling-corrected with the spell-word editor command (usually bound  to  M-s
       and M-S) and the entire input buffer with spell-line (usually bound to M-$).  The correct shell vari-able variable
       able can be set to `cmd' to correct the command name or `all' to correct the entire  line  each  time
       return  is  typed, and autocorrect can be set to correct the word to be completed before each comple-tion completion
       tion attempt.

       When spelling correction is invoked in any of these ways and the shell thinks that any  part  of  the
       command line is misspelled, it prompts with the corrected line:

           > set correct = cmd
           > lz /usr/bin
           CORRECT>ls /usr/bin (y|n|e|a)?

       One  can  answer  `y' or space to execute the corrected line, `e' to leave the uncorrected command in
       the input buffer, `a' to abort the command as if `^C' had been hit, and anything else to execute  the
       original line unchanged.

       Spelling  correction  recognizes  user-defined completions (see the complete builtin command).  If an
       input word in a position for which a completion is defined resembles a word in the  completion  list,
       spelling  correction  registers a misspelling and suggests the latter word as a correction.  However,
       if the input word does not match any of the possible completions for that position, spelling  correc-tion correction
       tion does not register a misspelling.

       Like  completion, spelling correction works anywhere in the line, pushing the rest of the line to the
       right and possibly leaving extra characters to the right of the cursor.

       Beware: spelling correction is not guaranteed to work the way one intends, and is provided mostly  as
       an experimental feature.  Suggestions and improvements are welcome.

   Editor commands (+)
       `bindkey'  lists key bindings and `bindkey -l' lists and briefly describes editor commands.  Only new
       or especially interesting editor commands are described here.  See emacs(1) and  vi(1)  for  descrip-tions descriptions
       tions of each editor's key bindings.

       The  character  or  characters  to  which  each  command is bound by default is given in parentheses.
       `^character' means a control character and `M-character' a meta character, typed as  escape-character
       on  terminals without a meta key.  Case counts, but commands that are bound to letters by default are
       bound to both lower- and uppercase letters for convenience.

       complete-word (tab)
               Completes a word as described under Completion and listing.

       complete-word-back (not bound)
               Like complete-word-fwd, but steps up from the end of the list.

       complete-word-fwd (not bound)
               Replaces the current word with the first word in the list of possible  completions.   May  be
               repeated  to  step  down  through the list.  At the end of the list, beeps and reverts to the
               incomplete word.

       complete-word-raw (^X-tab)
               Like complete-word, but ignores user-defined completions.

       copy-prev-word (M-^_)
               Copies the previous word in the current line into the input buffer.   See  also  insert-last-word. insert-lastword.

       dabbrev-expand (M-/)
               Expands  the current word to the most recent preceding one for which the current is a leading
               substring, wrapping around the history list (once) if  necessary.   Repeating  dabbrev-expand
               without  any  intervening  typing  changes to the next previous word etc., skipping identical
               matches much like history-search-backward does.

       delete-char (not bound)
               Deletes the character under the cursor.  See also delete-char-or-list-or-eof.

       delete-char-or-eof (not bound)
               Does delete-char if there is a character under the cursor or end-of-file on  an  empty  line.
               See also delete-char-or-list-or-eof.

       delete-char-or-list (not bound)
               Does  delete-char  if there is a character under the cursor or list-choices at the end of the
               line.  See also delete-char-or-list-or-eof.

       delete-char-or-list-or-eof (^D)
               Does delete-char if there is a character under the cursor, list-choices at  the  end  of  the
               line or end-of-file on an empty line.  See also those three commands, each of which does only
               a single action, and delete-char-or-eof, delete-char-or-list and list-or-eof, each  of  which
               does a different two out of the three.

       down-history (down-arrow, ^N)
               Like up-history, but steps down, stopping at the original input line.

       end-of-file (not bound)
               Signals  an end of file, causing the shell to exit unless the ignoreeof shell variable (q.v.)
               is set to prevent this.  See also delete-char-or-list-or-eof.

       expand-history (M-space)
               Expands history substitutions in the current  word.   See  History  substitution.   See  also
               magic-space, toggle-literal-history and the autoexpand shell variable.

       expand-glob (^X-*)
               Expands the glob-pattern to the left of the cursor.  See Filename substitution.

       expand-line (not bound)
               Like expand-history, but expands history substitutions in each word in the input buffer,

       expand-variables (^X-$)
               Expands the variable to the left of the cursor.  See Variable substitution.

       history-search-backward (M-p, M-P)
               Searches backwards through the history list for a command beginning with the current contents
               of the input buffer up to the cursor and copies it into the input buffer.  The search  string
               may be a glob-pattern (see Filename substitution) containing `*', `?', `[]' or `{}'.  up-his-tory up-history
               tory and down-history will proceed from the appropriate point in  the  history  list.   Emacs
               mode only.  See also history-search-forward and i-search-back.

       history-search-forward (M-n, M-N)
               Like history-search-backward, but searches forward.

       i-search-back (not bound)
               Searches  backward like history-search-backward, copies the first match into the input buffer
               with the cursor positioned at the end of the pattern, and prompts with `bck: ' and the  first
               match.   Additional  characters may be typed to extend the search, i-search-back may be typed
               to continue searching with the same pattern, wrapping around the history list  if  necessary,
               (i-search-back  must be bound to a single character for this to work) or one of the following
               special characters may be typed:

                   ^W      Appends the rest of the word under the cursor to the search pattern.
                   delete (or any character bound to backward-delete-char)
                           Undoes the effect of the last character typed and deletes a  character  from  the
                           search pattern if appropriate.
                   ^G      If  the  previous  search was successful, aborts the entire search.  If not, goes
                           back to the last successful search.
                   escape  Ends the search, leaving the current line in the input buffer.

               Any other character not bound to self-insert-command terminates the search, leaving the  cur-rent current
               rent  line  in  the  input buffer, and is then interpreted as normal input.  In particular, a
               carriage return causes the current line to be executed.  Emacs mode only.  See also i-search-fwd i-searchfwd
               fwd and history-search-backward.

       i-search-fwd (not bound)
               Like i-search-back, but searches forward.

       insert-last-word (M-_)
               Inserts  the  last  word  of  the previous input line (`!$') into the input buffer.  See also

       list-choices (M-^D)
               Lists completion possibilities as described under Completion and listing.  See  also  delete-char-or-list-or-eof deletechar-or-list-or-eof
               char-or-list-or-eof and list-choices-raw.

       list-choices-raw (^X-^D)
               Like list-choices, but ignores user-defined completions.

       list-glob (^X-g, ^X-G)
               Lists  (via  the ls-F builtin) matches to the glob-pattern (see Filename substitution) to the
               left of the cursor.

       list-or-eof (not bound)
               Does list-choices or end-of-file on an empty line.  See also delete-char-or-list-or-eof.

       magic-space (not bound)
               Expands history substitutions in the current line, like expand-history, and inserts a  space.
               magic-space is designed to be bound to the space bar, but is not bound by default.

       normalize-command (^X-?)
               Searches  for the current word in PATH and, if it is found, replaces it with the full path to
               the executable.  Special characters are quoted.  Aliases are expanded and quoted but commands
               within  aliases  are  not.   This command is useful with commands that take commands as argu-ments, arguments,
               ments, e.g., `dbx' and `sh -x'.

       normalize-path (^X-n, ^X-N)
               Expands the current word as described under the `expand' setting of the symlinks shell  vari-able. variable.

       overwrite-mode (unbound)
               Toggles between input and overwrite modes.

       run-fg-editor (M-^Z)
               Saves the current input line and looks for a stopped job with a name equal to the last compo-nent component
               nent of the file name part of the EDITOR or VISUAL environment variables, or, if  neither  is
               set,  `ed'  or `vi'.  If such a job is found, it is restarted as if `fg %job' had been typed.
               This is used to toggle back and forth between an editor and the shell  easily.   Some  people
               bind this command to `^Z' so they can do this even more easily.

       run-help (M-h, M-H)
               Searches for documentation on the current command, using the same notion of `current command'
               as the completion routines, and prints it.  There is no way  to  use  a  pager;  run-help  is
               designed  for  short help files.  If the special alias helpcommand is defined, it is run with
               the command name as a sole argument.  Else, documentation should be  in  a  file  named,,
     , command.1, command.6, command.8 or command, which should be in one of the directo-ries directories
               ries listed in the HPATH environment variable.  If there is more than one help file only  the
               first is printed.

       self-insert-command (text characters)
               In insert mode (the default), inserts the typed character into the input line after the char-acter character
               acter under the cursor.  In overwrite mode, replaces the character under the cursor with  the
               typed character.  The input mode is normally preserved between lines, but the inputmode shell
               variable can be set to `insert' or `overwrite' to put the editor in that mode at  the  begin-ning beginning
               ning of each line.  See also overwrite-mode.

       sequence-lead-in (arrow prefix, meta prefix, ^X)
               Indicates  that the following characters are part of a multi-key sequence.  Binding a command
               to a multi-key sequence really creates two bindings: the first character to  sequence-lead-in
               and  the  whole  sequence  to the command.  All sequences beginning with a character bound to
               sequence-lead-in are effectively bound to undefined-key unless bound to another command.

       spell-line (M-$)
               Attempts to correct the spelling of each word in  the  input  buffer,  like  spell-word,  but
               ignores words whose first character is one of `-', `!', `^' or `%', or which contain `\', `*'
               or `?', to avoid problems with switches, substitutions and the like.   See  Spelling  correc-tion. correction.

       spell-word (M-s, M-S)
               Attempts  to correct the spelling of the current word as described under Spelling correction.
               Checks each component of a word which appears to be a pathname.

       toggle-literal-history (M-r, M-R)
               Expands or `unexpands' history substitutions in the input buffer.   See  also  expand-history
               and the autoexpand shell variable.

       undefined-key (any unbound key)

       up-history (up-arrow, ^P)
               Copies the previous entry in the history list into the input buffer.  If histlit is set, uses
               the literal form of the entry.  May be repeated to step up through the history list, stopping
               at the top.

       vi-search-back (?)
               Prompts  with  `?'  for a search string (which may be a glob-pattern, as with history-search-backward), history-searchbackward),
               backward), searches for it and copies it into the input buffer.  The bell rings if  no  match
               is  found.   Hitting  return  ends  the search and leaves the last match in the input buffer.
               Hitting escape ends the search and executes the match.  vi mode only.

       vi-search-fwd (/)
               Like vi-search-back, but searches forward.

       which-command (M-?)
               Does a which (see the description of the builtin command) on the  first  word  of  the  input

       yank-pop (M-y)
               When  executed  immediately after a yank or another yank-pop, replaces the yanked string with
               the next previous string from the killring. This also has the effect of  rotating  the  kill-ring, killring,
               ring,  such that this string will be considered the most recently killed by a later yank com-mand. command.
               mand. Repeating yank-pop will cycle through the killring any number of times.

   Lexical structure
       The shell splits input lines into words at blanks and tabs.  The special characters  `&',  `|',  `;',
       `<',  `>',  `(',  and  `)'  and  the doubled characters `&&', `||', `<<' and `>>' are always separate
       words, whether or not they are surrounded by whitespace.

       When the shell's input is not a terminal, the character `#' is taken to begin a  comment.   Each  `#'
       and the rest of the input line on which it appears is discarded before further parsing.

       A  special character (including a blank or tab) may be prevented from having its special meaning, and
       possibly made part of another word, by preceding it with a backslash (`\') or enclosing it in  single
       (`''),  double (`"') or backward (``') quotes.  When not otherwise quoted a newline preceded by a `\'
       is equivalent to a blank, but inside quotes this sequence results in a newline.

       Furthermore, all Substitutions (see below) except History substitution can be prevented by  enclosing
       the  strings  (or parts of strings) in which they appear with single quotes or by quoting the crucial
       character(s) (e.g., `$' or ``' for Variable substitution or Command substitution  respectively)  with
       `\'.   (Alias  substitution  is no exception: quoting in any way any character of a word for which an
       alias has been defined prevents substitution of the alias.  The usual way of quoting an alias  is  to
       precede  it  with  a  backslash.)  History substitution is prevented by backslashes but not by single
       quotes.  Strings quoted with double or backward quotes undergo Variable substitution and Command sub-stitution, substitution,
       stitution, but other substitutions are prevented.

       Text  inside single or double quotes becomes a single word (or part of one).  Metacharacters in these
       strings, including blanks and tabs, do not form separate words.  Only in one special case  (see  Com-mand Command
       mand  substitution below) can a double-quoted string yield parts of more than one word; single-quoted
       strings never do.  Backward quotes are special: they signal Command substitution  (q.v.),  which  may
       result in more than one word.

       Quoting  complex  strings,  particularly  strings which themselves contain quoting characters, can be
       confusing.  Remember that quotes need not be used as they are in human writing!  It may be easier  to
       quote  not  an  entire string, but only those parts of the string which need quoting, using different
       types of quoting to do so if appropriate.

       The backslash_quote shell variable (q.v.) can be set to make backslashes always quote `\',  `'',  and
       `"'.   (+)  This  may  make  complex  quoting  tasks easier, but it can cause syntax errors in csh(1)

       We now describe the various transformations the shell performs on the input in  the  order  in  which
       they  occur.   We  note  in passing the data structures involved and the commands and variables which
       affect them.  Remember that substitutions can be prevented by  quoting  as  described  under  Lexical

   History substitution
       Each  command, or ``event'', input from the terminal is saved in the history list.  The previous com-mand command
       mand is always saved, and the history shell variable can be set to a number to save  that  many  com-mands. commands.
       mands.   The  histdup shell variable can be set to not save duplicate events or consecutive duplicate

       Saved commands are numbered sequentially from 1 and stamped with the time.  It is not usually  neces-sary necessary
       sary  to use event numbers, but the current event number can be made part of the prompt by placing an
       `!' in the prompt shell variable.

       The shell actually saves history in expanded and literal (unexpanded) forms.  If  the  histlit  shell
       variable is set, commands that display and store history use the literal form.

       The  history  builtin  command  can print, store in a file, restore and clear the history list at any
       time, and the savehist and histfile shell variables can be can be set to store the history list auto-matically automatically
       matically on logout and restore it on login.

       History  substitutions introduce words from the history list into the input stream, making it easy to
       repeat commands, repeat arguments of a previous command in the current command, or fix spelling  mis-takes mistakes
       takes in the previous command with little typing and a high degree of confidence.

       History substitutions begin with the character `!'.  They may begin anywhere in the input stream, but
       they do not nest.  The `!' may be preceded by a `\' to prevent its special meaning; for  convenience,
       a  `!' is passed unchanged when it is followed by a blank, tab, newline, `=' or `('.  History substi-tutions substitutions
       tutions also occur when an input line begins with `^'.  This special abbreviation will  be  described
       later.   The  characters  used to signal history substitution (`!' and `^') can be changed by setting
       the histchars shell variable.  Any input line which contains a history substitution is printed before
       it is executed.

       A  history  substitution  may  have  an ``event specification'', which indicates the event from which
       words are to be taken, a ``word designator'', which selects particular words from the  chosen  event,
       and/or a ``modifier'', which manipulates the selected words.

       An event specification can be

           n       A number, referring to a particular event
           -n      An offset, referring to the event n before the current event
           #       The  current event.  This should be used carefully in csh(1), where there is no check for
                   recursion.  tcsh allows 10 levels of recursion.  (+)
           !       The previous event (equivalent to `-1')
           s       The most recent event whose first word begins with the string s
           ?s?     The most recent event which contains the string s.  The second `?' can be omitted  if  it
                   is immediately followed by a newline.

       For example, consider this bit of someone's history list:

            9  8:30    nroff -man
           10  8:31    cp
           11  8:36    vi
           12  8:37    diff

       The commands are shown with their event numbers and time stamps.  The current event, which we haven't
       typed in yet, is event 13.  `!11' and `!-2' refer to event 11.  `!!' refers to  the  previous  event,
       12.   `!!'  can be abbreviated `!' if it is followed by `:' (`:' is described below).  `!n' refers to
       event 9, which begins with `n'.  `!?old?' also refers to event 12,  which  contains  `old'.   Without
       word  designators or modifiers history references simply expand to the entire event, so we might type
       `!cp' to redo the copy command or `!!|more' if the `diff' output scrolled off the top of the  screen.

       History references may be insulated from the surrounding text with braces if necessary.  For example,
       `!vdoc' would look for a command beginning with `vdoc', and, in  this  example,  not  find  one,  but
       `!{v}doc' would expand unambiguously to `vi wumpus.mandoc'.  Even in braces, history substitutions do
       not nest.

       (+) While csh(1) expands, for example, `!3d' to event 3 with the letter  `d'  appended  to  it,  tcsh
       expands  it  to  the last event beginning with `3d'; only completely numeric arguments are treated as
       event numbers.  This makes it possible to recall events beginning with numbers.  To expand  `!3d'  as
       in csh(1) say `!{3}d'.

       To select words from an event we can follow the event specification by a `:' and a designator for the
       desired words.  The words of an input line are numbered from 0,  the  first  (usually  command)  word
       being 0, the second word (first argument) being 1, etc.  The basic word designators are:

           0       The first (command) word
           n       The nth argument
           ^       The first argument, equivalent to `1'
           $       The last argument
           %       The word matched by an ?s? search
           x-y     A range of words
           -y      Equivalent to `_-y'
           *       Equivalent to `^-$', but returns nothing if the event contains only 1 word
           x*      Equivalent to `x-$'
           x-      Equivalent to `x*', but omitting the last word (`$')

       Selected  words  are  inserted  into  the  command line separated by single blanks.  For example, the
       `diff' command in the previous example might have been typed as `diff !!:1.old !!:1' (using  `:1'  to
       select the first argument from the previous event) or `diff !-2:2 !-2:1' to select and swap the argu-ments arguments
       ments from the `cp' command.  If we didn't care about the order of the  `diff'  we  might  have  said
       `diff  !-2:1-2'  or  simply  `diff  !-2:*'.   The `cp' command might have been written `cp
       !#:1.old', using `#' to refer to the current event.  `!n:-'  would  reuse  the  first  two
       words from the `nroff' command to say `nroff -man'.

       The  `:'  separating  the event specification from the word designator can be omitted if the argument
       selector begins with a `^', `$', `*', `%' or `-'.  For example, our `diff' command  might  have  been
       `diff  !!^.old  !!^'  or,  equivalently, `diff !!$.old !!$'.  However, if `!!' is abbreviated `!', an
       argument selector beginning with `-' will be interpreted as an event specification.

       A history reference may have a word designator but no event specification.  It  then  references  the
       previous  command.   Continuing our `diff' example, we could have said simply `diff !^.old !^' or, to
       get the arguments in the opposite order, just `diff !*'.

       The word or words in a history reference can be edited, or ``modified'', by following it with one  or
       more modifiers, each preceded by a `:':

           h       Remove a trailing pathname component, leaving the head.
           t       Remove all leading pathname components, leaving the tail.
           r       Remove a filename extension `.xxx', leaving the root name.
           e       Remove all but the extension.
           u       Uppercase the first lowercase letter.
           l       Lowercase the first uppercase letter.
           s/l/r/  Substitute  l  for  r.   l  is simply a string like r, not a regular expression as in the
                   eponymous ed(1) command.  Any character may be used as the delimiter in place of  `/';  a
                   `\'  can  be  used  to quote the delimiter inside l and r.  The character `&' in the r is
                   replaced by l; `\' also quotes `&'.  If l is empty (``''), the l from a previous  substi-tution substitution
                   tution  or  the  s from a previous search or event number in event specification is used.
                   The trailing delimiter may be omitted if it is immediately followed by a newline.
           &       Repeat the previous substitution.
           g       Apply the following modifier once to each word.
           a (+)   Apply the following modifier as many times as possible to a single word.  `a' and `g' can
                   be  used together to apply a modifier globally.  With the `s' modifier, only the patterns
                   contained in the original word are substituted, not patterns that contain  any  substitu-tion substitution
                   tion result.
           p       Print the new command line but do not execute it.
           q       Quote the substituted words, preventing further substitutions.
           x       Like q, but break into words at blanks, tabs and newlines.

       Modifiers  are applied to only the first modifiable word (unless `g' is used).  It is an error for no
       word to be modifiable.

       For example, the `diff' command might have been written as `diff !#^:r', using `:r' to
       remove `.old' from the first argument on the same line (`!#^').  We could say `echo hello out there',
       then `echo !*:u' to capitalize `hello', `echo !*:au' to say it out loud, or `echo !*:agu'  to  really
       shout.   We  might  follow  `mail  -s  "I forgot my password" rot' with `!:s/rot/root' to correct the
       spelling of `root' (but see Spelling correction for a different approach).

       There is a special abbreviation for substitutions.  `^', when it is the first character on  an  input
       line,  is  equivalent to `!:s^'.  Thus we might have said `^rot^root' to make the spelling correction
       in the previous example.  This is the only history substitution which does not explicitly begin  with

       (+) In csh as such, only one modifier may be applied to each history or variable expansion.  In tcsh,
       more than one may be used, for example

           % mv /usr/man/man1/wumpus.1
           % man !$:t:r
           man wumpus

       In csh, the result would be `wumpus.1:r'.  A substitution followed by a colon may need  to  be  insu-lated insulated
       lated from it with braces:

           > mv a.out /usr/games/wumpus
           > setenv PATH !$:h:$PATH
           Bad ! modifier: $.
           > setenv PATH !{-2$:h}:$PATH
           setenv PATH /usr/games:/bin:/usr/bin:.

       The first attempt would succeed in csh but fails in tcsh, because tcsh expects another modifier after
       the second colon rather than `$'.

       Finally, history can be accessed through the  editor  as  well  as  through  the  substitutions  just
       described.   The  up- and down-history, history-search-backward and -forward, i-search-back and -fwd,
       vi-search-back and -fwd, copy-prev-word and insert-last-word editor commands search for events in the
       history list and copy them into the input buffer.  The toggle-literal-history editor command switches
       between the expanded and literal forms of history lines in  the  input  buffer.   expand-history  and
       expand-line  expand  history substitutions in the current word and in the entire input buffer respec-tively. respectively.

   Alias substitution
       The shell maintains a list of aliases which can be set, unset and printed by the  alias  and  unalias
       commands.   After a command line is parsed into simple commands (see Commands) the first word of each
       command, left-to-right, is checked to see if it has an alias.  If so, the first word is  replaced  by
       the  alias.   If  the alias contains a history reference, it undergoes History substitution (q.v.) as
       though the original command were the previous input line.  If the alias does not  contain  a  history
       reference, the argument list is left untouched.

       Thus if the alias for `ls' were `ls -l' the command `ls /usr' would become `ls -l /usr', the argument
       list here being undisturbed.  If the alias for `lookup' were `grep !^ /etc/passwd' then `lookup bill'
       would become `grep bill /etc/passwd'.  Aliases can be used to introduce parser metasyntax.  For exam-ple, example,
       ple, `alias print 'pr \!* | lpr'' defines a ``command'' (`print') which pr(1)s its arguments  to  the
       line printer.

       Alias substitution is repeated until the first word of the command has no alias.  If an alias substi-tution substitution
       tution does not change the first word (as in the previous example) it is flagged to prevent  a  loop.
       Other loops are detected and cause an error.

       Some aliases are referred to by the shell; see Special aliases.

   Variable substitution
       The  shell  maintains  a  list of variables, each of which has as value a list of zero or more words.
       The values of shell variables can be displayed and changed with the set and unset commands.  The sys-tem system
       tem  maintains  its  own  list of ``environment'' variables.  These can be displayed and changed with
       printenv, setenv and unsetenv.

       (+) Variables may be made read-only with `set -r' (q.v.)  Read-only variables may not be modified  or
       unset;  attempting  to  do  so  will  cause an error.  Once made read-only, a variable cannot be made
       writable, so `set -r' should be used with caution.  Environment variables cannot be made read-only.

       Some variables are set by the shell or referred to by it.  For instance,  the  argv  variable  is  an
       image  of  the  shell's  argument list, and words of this variable's value are referred to in special
       ways.  Some of the variables referred to by the shell are toggles; the shell does not care what their
       value  is,  only  whether  they are set or not.  For instance, the verbose variable is a toggle which
       causes command input to be echoed.  The -v command line option sets  this  variable.   Special  shell
       variables lists all variables which are referred to by the shell.

       Other  operations  treat  variables  numerically.  The `@' command permits numeric calculations to be
       performed and the result assigned to a variable.  Variable values are, however, always represented as
       (zero  or more) strings.  For the purposes of numeric operations, the null string is considered to be
       zero, and the second and subsequent words of multi-word values are ignored.

       After the input line is aliased and parsed, and before each command is executed,  variable  substitu-tion substitution
       tion is performed keyed by `$' characters.  This expansion can be prevented by preceding the `$' with
       a `\' except within `"'s where it always occurs, and within `''s  where  it  never  occurs.   Strings
       quoted  by  ``'  are  interpreted later (see Command substitution below) so `$' substitution does not
       occur there until later, if at all.  A `$' is passed unchanged if followed by a blank, tab,  or  end-of-line. endof-line.

       Input/output  redirections  are recognized before variable expansion, and are variable expanded sepa-rately. separately.
       rately.  Otherwise, the command name and entire argument list are expanded together.  It is thus pos-sible possible
       sible for the first (command) word (to this point) to generate more than one word, the first of which
       becomes the command name, and the rest of which become arguments.

       Unless enclosed in `"' or given the `:q' modifier the results of variable substitution may eventually
       be  command  and filename substituted.  Within `"', a variable whose value consists of multiple words
       expands to a (portion of a) single word, with the words of the variable's value separated by  blanks.
       When  the  `:q' modifier is applied to a substitution the variable will expand to multiple words with
       each word separated by a blank and quoted to prevent later command or filename substitution.

       The following metasequences are provided for  introducing  variable  values  into  the  shell  input.
       Except as noted, it is an error to reference a variable which is not set.

       ${name} Substitutes the words of the value of variable name, each separated by a blank.  Braces insu-late insulate
               late name from following characters which would otherwise be part  of  it.   Shell  variables
               have names consisting of letters and digits starting with a letter.  The underscore character
               is considered a letter.  If name is not a shell variable, but is set in the environment, then
               that  value  is  returned  (but some of the other forms given below are not available in this
               Substitutes only the selected words from the value of name.  The selector is subjected to `$'
               substitution and may consist of a single number or two numbers separated by a `-'.  The first
               word of a variable's value is numbered `1'.  If the first number of a  range  is  omitted  it
               defaults  to  `1'.   If  the  last member of a range is omitted it defaults to `$#name'.  The
               selector `*' selects all words.  It is not an error for a range to be  empty  if  the  second
               argument is omitted or in range.
       $0      Substitutes  the name of the file from which command input is being read.  An error occurs if
               the name is not known.
               Equivalent to `$argv[number]'.
       $*      Equivalent to `$argv', which is equivalent to `$argv[*]'.

       The `:' modifiers described under History substitution, except for `:p', can be applied to  the  sub-stitutions substitutions
       stitutions  above.   More than one may be used.  (+) Braces may be needed to insulate a variable sub-stitution substitution
       stitution from a literal colon just as with History substitution (q.v.); any  modifiers  must  appear
       within the braces.

       The following substitutions can not be modified with `:' modifiers.

               Substitutes the string `1' if name is set, `0' if it is not.
       $?0     Substitutes  `1'  if  the  current  input filename is known, `0' if it is not.  Always `0' in
               interactive shells.
               Substitutes the number of words in name.
       $#      Equivalent to `$#argv'.  (+)
               Substitutes the number of characters in name.  (+)
               Substitutes the number of characters in $argv[number].  (+)
       $?      Equivalent to `$status'.  (+)
       $$      Substitutes the (decimal) process number of the (parent) shell.
       $!      Substitutes the (decimal) process number of the  last  background  process  started  by  this
               shell.  (+)
       $_      Substitutes the command line of the last command executed.  (+)
       $<      Substitutes  a  line  from the standard input, with no further interpretation thereafter.  It
               can be used to read from the keyboard in a shell script.  (+) While csh always quotes $<,  as
               if it were equivalent to `$<:q', tcsh does not.  Furthermore, when tcsh is waiting for a line
               to be typed the user may type an interrupt to interrupt the sequence into which the  line  is
               to be substituted, but csh does not allow this.

       The  editor  command  expand-variables, normally bound to `^X-$', can be used to interactively expand
       individual variables.

   Command, filename and directory stack substitution
       The remaining substitutions are applied selectively to the arguments of builtin commands.  This means
       that portions of expressions which are not evaluated are not subjected to these expansions.  For com-
       mands which are not internal to the shell, the command name is substituted separately from the  argu-ment argument
       ment list.  This occurs very late, after input-output redirection is performed, and in a child of the
       main shell.

   Command substitution
       Command substitution is indicated by a command enclosed in ``'.  The output from such  a  command  is
       broken into separate words at blanks, tabs and newlines, and null words are discarded.  The output is
       variable and command substituted and put in place of the original string.

       Command substitutions inside double quotes (`"') retain blanks and  tabs;  only  newlines  force  new
       words.   The  single  final newline does not force a new word in any case.  It is thus possible for a
       command substitution to yield only part of a word, even if the command outputs a complete line.

       By default, the shell since version 6.12 replaces all newline and carriage return characters  in  the
       command  by  spaces.   If this is switched off by unsetting csubstnonl, newlines separate commands as

   Filename substitution
       If a word contains any of the characters `*', `?', `[' or `{' or begins with the character `~' it  is
       a  candidate  for filename substitution, also known as ``globbing''.  This word is then regarded as a
       pattern (``glob-pattern''), and replaced with an alphabetically sorted list of file names which match
       the pattern.

       In  matching  filenames,  the character `.' at the beginning of a filename or immediately following a
       `/', as well as the character `/' must be matched explicitly.  The character `*' matches  any  string
       of  characters,  including  the  null  string.   The character `?' matches any single character.  The
       sequence `[...]' matches any one of the characters enclosed.  Within `[...]', a  pair  of  characters
       separated by `-' matches any character lexically between the two.

       (+)  Some glob-patterns can be negated: The sequence `[^...]' matches any single character not speci-fied specified
       fied by the characters and/or ranges of characters in the braces.

       An entire glob-pattern can also be negated with `^':

           > echo *
           bang crash crunch ouch
           > echo ^cr*
           bang ouch

       Glob-patterns which do not use `?', `*', or `[]' or which use `{}' or `~'  (below)  are  not  negated

       The  metanotation  `a{b,c,d}e'  is  a shorthand for `abe ace ade'.  Left-to-right order is preserved:
       `/usr/source/s1/{oldls,ls}.c' expands to `/usr/source/s1/oldls.c /usr/source/s1/ls.c'.   The  results
       of matches are sorted separately at a low level to preserve this order: `../{memo,*box}' might expand
       to `../memo ../box ../mbox'.  (Note that `memo' was not sorted with the results of matching  `*box'.)
       It is not an error when this construct expands to files which do not exist, but it is possible to get
       an error from a command to which the expanded list is passed.  This construct may be  nested.   As  a
       special case the words `{', `}' and `{}' are passed undisturbed.

       The  character  `~' at the beginning of a filename refers to home directories.  Standing alone, i.e.,
       `~', it expands to the invoker's home directory as reflected in the value of the home shell variable.
       When  followed  by  a  name consisting of letters, digits and `-' characters the shell searches for a
       user with that name and substitutes their home directory; thus `~ken' might expand to `/usr/ken'  and
       `~ken/chmach'  to  `/usr/ken/chmach'.   If  the character `~' is followed by a character other than a
       letter or `/' or appears elsewhere than at the beginning of a word, it is left undisturbed.   A  com-mand command
       mand  like  `setenv MANPATH /usr/man:/usr/local/man:~/lib/man' does not, therefore, do home directory
       substitution as one might hope.

       It is an error for a glob-pattern containing `*', `?', `[' or `~', with or without `^', not to  match
       any  files.   However,  only one pattern in a list of glob-patterns must match a file (so that, e.g.,
       `rm *.a *.c *.o' would fail only if there were no files in the  current  directory  ending  in  `.a',
       `.c',  or  `.o'),  and  if  the nonomatch shell variable is set a pattern (or list of patterns) which
       matches nothing is left unchanged rather than causing an error.

       The noglob shell variable can be set to prevent filename substitution,  and  the  expand-glob  editor
       command,  normally bound to `^X-*', can be used to interactively expand individual filename substitu-tions. substitutions.

   Directory stack substitution (+)
       The directory stack is a list of directories, numbered from zero, used by the pushd,  popd  and  dirs
       builtin  commands  (q.v.).  dirs can print, store in a file, restore and clear the directory stack at
       any time, and the savedirs and dirsfile shell variables can be set to store the directory stack auto-matically automatically
       matically  on logout and restore it on login.  The dirstack shell variable can be examined to see the
       directory stack and set to put arbitrary directories into the directory stack.

       The character `=' followed by one or more digits expands to an entry in  the  directory  stack.   The
       special case `=-' expands to the last directory in the stack.  For example,

           > dirs -v
           0       /usr/bin
           1       /usr/spool/uucp
           2       /usr/accts/sys
           > echo =1
           > echo =0/calendar
           > echo =-/usr/accts/sys =/usr/accts/sys

       The  noglob and nonomatch shell variables and the expand-glob editor command apply to directory stack
       as well as filename substitutions.

   Other substitutions (+)
       There are several more transformations involving filenames, not strictly related  to  the  above  but
       mentioned here for completeness.  Any filename may be expanded to a full path when the symlinks vari-able variable
       able (q.v.) is set to `expand'.  Quoting prevents this expansion, and the normalize-path editor  com-mand command
       mand  does  it  on  demand.   The normalize-command editor command expands commands in PATH into full
       paths on demand.  Finally, cd and pushd interpret `-' as the old working directory (equivalent to the
       shell variable owd).  This is not a substitution at all, but an abbreviation recognized by only those
       commands.  Nonetheless, it too can be prevented by quoting.

       The next three sections describe how the shell executes commands and deals with their input and  out-put. output.

   Simple commands, pipelines and sequences
       A  simple command is a sequence of words, the first of which specifies the command to be executed.  A
       series of simple commands joined by `|' characters forms a pipeline.  The output of each command in a
       pipeline is connected to the input of the next.

       Simple  commands  and  pipelines  may be joined into sequences with `;', and will be executed sequen-tially. sequentially.
       tially.  Commands and pipelines can also be joined into sequences with `||' or `&&',  indicating,  as
       in  the  C  language,  that  the second is to be executed only if the first fails or succeeds respec-tively. respectively.

       A simple command, pipeline or sequence may be placed in parentheses, `()', to form a simple  command,
       which  may  in turn be a component of a pipeline or sequence.  A command, pipeline or sequence can be
       executed without waiting for it to terminate by following it with an `&'.

   Builtin and non-builtin command execution
       Builtin commands are executed within the shell.  If any component of a pipeline except the last is  a
       builtin command, the pipeline is executed in a subshell.

       Parenthesized commands are always executed in a subshell.

           (cd; pwd); pwd

       thus  prints the home directory, leaving you where you were (printing this after the home directory),

           cd; pwd

       leaves you in the home directory.  Parenthesized commands are most often  used  to  prevent  cd  from
       affecting the current shell.

       When  a command to be executed is found not to be a builtin command the shell attempts to execute the
       command via execve(2).  Each word in the variable path names a directory in which the shell will look
       for the command.  If the shell is not given a -f option, the shell hashes the names in these directo-ries directories
       ries into an internal table so that it will try an execve(2) in only a directory  where  there  is  a
       possibility that the command resides there.  This greatly speeds command location when a large number
       of directories are present in the search path. This hashing mechanism is not used:

       1.  If hashing is turned explicitly off via unhash.

       2.  If the shell was given a -f argument.

       3.  For each directory component of path which does not begin with a `/'.

       4.  If the command contains a `/'.

       In the above four cases the shell concatenates each component of the path vector with the given  com-mand command
       mand  name  to  form a path name of a file which it then attempts to execute it. If execution is suc-cessful, successful,
       cessful, the search stops.

       If the file has execute permissions but is not an executable to the system (i.e., it  is  neither  an
       executable  binary nor a script that specifies its interpreter), then it is assumed to be a file con-taining containing
       taining shell commands and a new shell is spawned to read it.  The shell special alias may be set  to
       specify an interpreter other than the shell itself.

       On  systems  which do not understand the `#!' script interpreter convention the shell may be compiled
       to emulate it; see the version shell variable.  If so, the shell checks the first line of the file to
       see  if  it  is of the form `#!interpreter arg ...'.  If it is, the shell starts interpreter with the
       given args and feeds the file to it on standard input.

       The standard input and standard output of a command may be redirected with the following syntax:

       < name  Open file name (which is first variable, command  and  filename  expanded)  as  the  standard
       << word Read the shell input up to a line which is identical to word.  word is not subjected to vari-
               able, filename or command substitution, and each input line is compared to  word  before  any
               substitutions  are  done on this input line.  Unless a quoting `\', `"', `' or ``' appears in
               word variable and command substitution is performed on the intervening lines, allowing `\' to
               quote  `$',  `\' and ``'.  Commands which are substituted have all blanks, tabs, and newlines
               preserved, except for the final newline which is dropped.  The resultant text is placed in an
               anonymous temporary file which is given to the command as standard input.
       > name
       >! name
       >& name
       >&! name
               The  file name is used as standard output.  If the file does not exist then it is created; if
               the file exists, it is truncated, its previous contents being lost.

               If the shell variable noclobber is set, then the file must not exist or be a  character  spe-cial special
               cial file (e.g., a terminal or `/dev/null') or an error results.  This helps prevent acciden-tal accidental
               tal destruction of files.  In this case the `!' forms can be used to suppress this check.

               The forms involving `&' route the diagnostic output into the specified file as  well  as  the
               standard output.  name is expanded in the same way as `<' input filenames are.
       >> name
       >>& name
       >>! name
       >>&! name
               Like  `>',  but  appends  output to the end of name.  If the shell variable noclobber is set,
               then it is an error for the file not to exist, unless one of the `!' forms is given.

       A command receives the environment in which the shell was invoked as  modified  by  the  input-output
       parameters  and  the  presence of the command in a pipeline.  Thus, unlike some previous shells, com-mands commands
       mands run from a file of shell commands have no access to the text of the commands by default; rather
       they  receive the original standard input of the shell.  The `<<' mechanism should be used to present
       inline data.  This permits shell command scripts to function as components of  pipelines  and  allows
       the  shell  to block read its input.  Note that the default standard input for a command run detached
       is not the empty file /dev/null, but the original standard input of the shell.  If this is a terminal
       and  if the process attempts to read from the terminal, then the process will block and the user will
       be notified (see Jobs).

       Diagnostic output may be directed through a pipe with the standard output.  Simply use the form  `|&'
       rather than just `|'.

       The  shell  cannot presently redirect diagnostic output without also redirecting standard output, but
       `(command > output-file) >& error-file' is often an acceptable  workaround.   Either  output-file  or
       error-file may be `/dev/tty' to send output to the terminal.

       Having  described  how the shell accepts, parses and executes command lines, we now turn to a variety
       of its useful features.

   Control flow
       The shell contains a number of commands which can be used to regulate the flow of control in  command
       files (shell scripts) and (in limited but useful ways) from terminal input.  These commands all oper-ate operate
       ate by forcing the shell to reread or skip in its input and, due to the implementation, restrict  the
       placement of some of the commands.

       The  foreach,  switch,  and  while  statements, as well as the if-then-else form of the if statement,
       require that the major keywords appear in a single simple command on an input line as shown below.

       If the shell's input is not seekable, the shell buffers up input whenever a loop is  being  read  and
       performs  seeks  in  this  internal  buffer to accomplish the rereading implied by the loop.  (To the
       extent that this allows, backward gotos will succeed on non-seekable inputs.)

       The if, while and exit builtin commands use expressions with a common syntax.   The  expressions  can
       include  any  of the operators described in the next three sections.  Note that the @ builtin command
       (q.v.) has its own separate syntax.

   Logical, arithmetical and comparison operators
       These operators are similar to those of C and have the same precedence.  They include

           ||  &&  |  ^  &  ==  !=  =~  !~  <=  >=
           <  > <<  >>  +  -  *  /  %  !  ~  (  )

       Here the precedence increases to the right, `==' `!=' `=~' and `!~', `<=' `>=' `<' and `>', `<<'  and
       `>>',  `+' and `-', `*' `/' and `%' being, in groups, at the same level.  The `==' `!=' `=~' and `!~'
       operators compare their arguments as strings; all others operate on numbers.  The operators `=~'  and
       `!~' are like `!=' and `==' except that the right hand side is a glob-pattern (see Filename substitu-tion) substitution)
       tion) against which the left hand operand is matched.  This reduces the need for use  of  the  switch
       builtin command in shell scripts when all that is really needed is pattern matching.

       Null or missing arguments are considered `0'.  The results of all expressions are strings, which rep-resent represent
       resent decimal numbers.  It is important to note that no two components of an expression  can  appear
       in  the same word; except when adjacent to components of expressions which are syntactically signifi-cant significant
       cant to the parser (`&' `|' `<' `>' `(' `)') they should be surrounded by spaces.

   Command exit status
       Commands can be executed in expressions and their exit status returned by enclosing  them  in  braces
       (`{}').   Remember that the braces should be separated from the words of the command by spaces.  Com-mand Command
       mand executions succeed, returning true, i.e., `1', if the command exits  with  status  0,  otherwise
       they fail, returning false, i.e., `0'.  If more detailed status information is required then the com-mand command
       mand should be executed outside of an expression and the status shell variable examined.

   File inquiry operators
       Some of these operators perform true/false tests on files and related objects.  They are of the  form
       -op file, where op is one of

           r   Read access
           w   Write access
           x   Execute access
           X   Executable  in the path or shell builtin, e.g., `-X ls' and `-X ls-F' are generally true, but
               `-X /bin/ls' is not (+)
           e   Existence
           o   Ownership
           z   Zero size
           s   Non-zero size (+)
           f   Plain file
           d   Directory
           l   Symbolic link (+) *
           b   Block special file (+)
           c   Character special file (+)
           p   Named pipe (fifo) (+) *
           S   Socket special file (+) *
           u   Set-user-ID bit is set (+)
           g   Set-group-ID bit is set (+)
           k   Sticky bit is set (+)
           t   file (which must be a digit) is an open file descriptor for a terminal device (+)
           R   Has been migrated (convex only) (+)
           L   Applies subsequent operators in a multiple-operator test to a symbolic link  rather  than  to
               the file to which the link points (+) *

       file  is command and filename expanded and then tested to see if it has the specified relationship to
       the real user.  If file does not exist or is inaccessible or, for the operators indicated by `*',  if
       the  specified file type does not exist on the current system, then all enquiries return false, i.e.,

       These operators may be combined for conciseness: `-xy file' is equivalent to `-x file  &&  -y  file'.
       (+) For example, `-fx' is true (returns `1') for plain executable files, but not for directories.

       L  may  be  used  in a multiple-operator test to apply subsequent operators to a symbolic link rather
       than to the file to which the link points.  For example, `-lLo' is true for links owned by the invok-ing invoking
       ing  user.  Lr, Lw and Lx are always true for links and false for non-links.  L has a different mean-ing meaning
       ing when it is the last operator in a multiple-operator test; see below.

       It is possible but not useful, and sometimes misleading, to combine operators which expect file to be
       a  file  with operators which do not, (e.g., X and t).  Following L with a non-file operator can lead
       to particularly strange results.

       Other operators return other information, i.e., not just `0' or `1'.  (+) They have the  same  format
       as before; op may be one of

           A       Last file access time, as the number of seconds since the epoch
           A:      Like A, but in timestamp format, e.g., `Fri May 14 16:36:10 1993'
           M       Last file modification time
           M:      Like M, but in timestamp format
           C       Last inode modification time
           C:      Like C, but in timestamp format
           D       Device number
           I       Inode number
           F       Composite file identifier, in the form device:inode
           L       The name of the file pointed to by a symbolic link
           N       Number of (hard) links
           P       Permissions, in octal, without leading zero
           P:      Like P, with leading zero
           Pmode   Equivalent  to  `-P  file  & mode', e.g., `-P22 file' returns `22' if file is writable by
                   group and other, `20' if by group only, and `0' if by neither
           Pmode:  Like Pmode, with leading zero
           U       Numeric userid
           U:      Username, or the numeric userid if the username is unknown
           G       Numeric groupid
           G:      Groupname, or the numeric groupid if the groupname is unknown
           Z       Size, in bytes

       Only one of these operators may appear in a multiple-operator test, and it must be  the  last.   Note
       that  L has a different meaning at the end of and elsewhere in a multiple-operator test.  Because `0'
       is a valid return value for many of these operators, they do not return  `0'  when  they  fail:  most
       return `-1', and F returns `:'.

       If  the  shell  is compiled with POSIX defined (see the version shell variable), the result of a file
       inquiry is based on the permission bits of the file and not on the result  of  the  access(2)  system
       call.   For example, if one tests a file with -w whose permissions would ordinarily allow writing but
       which is on a file system mounted read-only, the test will succeed in a POSIX shell  but  fail  in  a
       non-POSIX shell.

       File inquiry operators can also be evaluated with the filetest builtin command (q.v.) (+).

       The shell associates a job with each pipeline.  It keeps a table of current jobs, printed by the jobs
       command, and assigns them small integer numbers.  When a job is started asynchronously with `&',  the
       shell prints a line which looks like

           [1] 1234

       indicating  that  the  job  which was started asynchronously was job number 1 and had one (top-level)
       process, whose process id was 1234.

       If you are running a job and wish to do something else you may hit the suspend  key  (usually  `^Z'),
       which sends a STOP signal to the current job.  The shell will then normally indicate that the job has
       been `Suspended' and print another prompt.  If the listjobs shell variable is set, all jobs  will  be
       listed like the jobs builtin command; if it is set to `long' the listing will be in long format, like
       `jobs -l'.  You can then manipulate the state of the suspended job.  You can put it  in  the  ``back-ground'' ``background''
       ground''  with  the  bg command or run some other commands and eventually bring the job back into the
       ``foreground'' with fg.  (See also the run-fg-editor editor command.)  A `^Z'  takes  effect  immedi-ately immediately
       ately  and  is  like  an  interrupt  in that pending output and unread input are discarded when it is
       typed.  The wait builtin command causes the shell to wait for all background jobs to complete.

       The `^]' key sends a delayed suspend signal, which does not generate a STOP signal  until  a  program
       attempts  to read(2) it, to the current job.  This can usefully be typed ahead when you have prepared
       some commands for a job which you wish to stop after it has read them.  The `^Y'  key  performs  this
       function in csh(1); in tcsh, `^Y' is an editing command.  (+)

       A  job  being run in the background stops if it tries to read from the terminal.  Background jobs are
       normally allowed to produce output, but this can be disabled by giving the command `stty tostop'.  If
       you  set this tty option, then background jobs will stop when they try to produce output like they do
       when they try to read input.

       There are several ways to refer to jobs in the shell.  The character `%' introduces a job  name.   If
       you wish to refer to job number 1, you can name it as `%1'.  Just naming a job brings it to the fore-ground; foreground;
       ground; thus `%1' is a synonym for `fg %1', bringing job 1 back into the foreground.  Similarly, say-ing saying
       ing  `%1  &' resumes job 1 in the background, just like `bg %1'.  A job can also be named by an unam-biguous unambiguous
       biguous prefix of the string typed in to start it: `%ex' would normally  restart  a  suspended  ex(1)
       job, if there were only one suspended job whose name began with the string `ex'.  It is also possible
       to say `%?string' to specify a job whose text contains string, if there is only one such job.

       The shell maintains a notion of the current and previous jobs.  In output  pertaining  to  jobs,  the
       current  job  is marked with a `+' and the previous job with a `-'.  The abbreviations `%+', `%', and
       (by analogy with the syntax of the history mechanism) `%%' all refer to the  current  job,  and  `%-'
       refers to the previous job.

       The  job  control  mechanism requires that the stty(1) option `new' be set on some systems.  It is an
       artifact from a `new' implementation of the tty driver which allows generation of  interrupt  charac-ters characters
       ters  from  the keyboard to tell jobs to stop.  See stty(1) and the setty builtin command for details
       on setting options in the new tty driver.

   Status reporting
       The shell learns immediately whenever a process changes state.  It normally informs  you  whenever  a
       job  becomes  blocked  so  that  no  further  progress is possible, but only right before it prints a
       prompt.  This is done so that it does not otherwise disturb your work.   If,  however,  you  set  the
       shell variable notify, the shell will notify you immediately of changes of status in background jobs.
       There is also a shell command notify which marks a single process so that its status changes will  be
       immediately  reported.  By default notify marks the current process; simply say `notify' after start-ing starting
       ing a background job to mark it.

       When you try to leave the shell while jobs are stopped, you will be warned that `There are  suspended
       jobs.'  You may use the jobs command to see what they are.  If you do this or immediately try to exit
       again, the shell will not warn you a second time, and the suspended jobs will be terminated.

   Automatic, periodic and timed events (+)
       There are various ways to run commands and take other actions automatically at various times  in  the
       ``life cycle'' of the shell.  They are summarized here, and described in detail under the appropriate
       Builtin commands, Special shell variables and Special aliases.

       The sched builtin command puts commands in a scheduled-event list, to be executed by the shell  at  a
       given time.

       The  beepcmd, cwdcmd, periodic, precmd, postcmd, and jobcmd Special aliases can be set, respectively,
       to execute commands when the shell wants to ring the bell, when the working directory changes,  every
       tperiod  minutes, before each prompt, before each command gets executed, after each command gets exe-cuted, executed,
       cuted, and when a job is started or is brought into the foreground.

       The autologout shell variable can be set to log out or lock the shell after a given number of minutes
       of inactivity.

       The mail shell variable can be set to check for new mail periodically.

       The  printexitvalue  shell variable can be set to print the exit status of commands which exit with a
       status other than zero.

       The rmstar shell variable can be set to ask the user, when `rm *' is typed, if that  is  really  what
       was meant.

       The  time  shell  variable can be set to execute the time builtin command after the completion of any
       process that takes more than a given number of CPU seconds.

       The watch and who shell variables can be set to report when selected users log in or out, and the log
       builtin command reports on those users at any time.

   Native Language System support (+)
       The shell is eight bit clean (if so compiled; see the version shell variable) and thus supports char-acter character
       acter sets needing this capability.  NLS support differs depending on whether or not  the  shell  was
       compiled  to  use  the system's NLS (again, see version).  In either case, 7-bit ASCII is the default
       character code (e.g., the classification of which characters are printable) and sorting, and changing
       the LANG or LC_CTYPE environment variables causes a check for possible changes in these respects.

       When  using  the system's NLS, the setlocale(3) function is called to determine appropriate character
       code/classification and sorting (e.g., a 'en_CA.UTF-8' would yield  "UTF-8"  as  a  character  code).
       This  function  typically  examines  the LANG and LC_CTYPE environment variables; refer to the system
       documentation for further details.  When not using the system's NLS, the shell simulates it by assum-ing assuming
       ing  that the ISO 8859-1 character set is used whenever either of the LANG and LC_CTYPE variables are
       set, regardless of their values.  Sorting is not affected for the simulated NLS.

       In addition, with both real and simulated NLS, all printable characters in the range \200-\377, i.e.,
       those that have M-char bindings, are automatically rebound to self-insert-command.  The corresponding
       binding for the escape-char sequence, if any, is left alone.  These characters are not rebound if the
       NOREBIND  environment  variable is set.  This may be useful for the simulated NLS or a primitive real
       NLS which assumes full ISO 8859-1.  Otherwise, all M-char bindings in the range \240-\377 are  effec-tively effectively
       tively undone.  Explicitly rebinding the relevant keys with bindkey is of course still possible.

       Unknown characters (i.e., those that are neither printable nor control characters) are printed in the
       format \nnn.  If the tty is not in 8 bit mode, other 8 bit characters are printed by converting  them
       to  ASCII  and  using  standout mode.  The shell never changes the 7/8 bit mode of the tty and tracks
       user-initiated changes of 7/8 bit mode.  NLS users (or, for that matter, those who want to use a meta
       key)  may  need  to  explicitly set the tty in 8 bit mode through the appropriate stty(1) command in,
       e.g., the ~/.login file.

   OS variant support (+)
       A number of new builtin commands are provided to support features in  particular  operating  systems.
       All are described in detail in the Builtin commands section.

       On  systems that support TCF (aix-ibm370, aix-ps2), getspath and setspath get and set the system exe-cution execution
       cution path, getxvers and setxvers get and set the experimental version prefix and  migrate  migrates
       processes between sites.  The jobs builtin prints the site on which each job is executing.

       Under BS2000, bs2cmd executes commands of the underlying BS2000/OSD operating system.

       Under  Domain/OS, inlib adds shared libraries to the current environment, rootnode changes the rootn-ode rootnode
       ode and ver changes the systype.

       Under Mach, setpath is equivalent to Mach's setpath(1).

       Under Masscomp/RTU and Harris CX/UX, universe sets the universe.

       Under Harris CX/UX, ucb or att runs a command under the specified universe.

       Under Convex/OS, warp prints or sets the universe.

       The VENDOR, OSTYPE and MACHTYPE environment variables indicate  respectively  the  vendor,  operating
       system  and  machine  type  (microprocessor  class or machine model) of the system on which the shell
       thinks it is running.  These are particularly useful when sharing one's home directory  between  sev-eral several
       eral types of machines; one can, for example,

           set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)

       in one's ~/.login and put executables compiled for each machine in the appropriate directory.

       The version shell variable indicates what options were chosen when the shell was compiled.

       Note  also  the  newgrp  builtin, the afsuser and echo_style shell variables and the system-dependent
       locations of the shell's input files (see FILES).

   Signal handling
       Login shells ignore interrupts when reading the file  ~/.logout.   The  shell  ignores  quit  signals
       unless  started  with  -q.  Login shells catch the terminate signal, but non-login shells inherit the
       terminate behavior from their parents.  Other signals have the values which the shell inherited  from
       its parent.

       In  shell  scripts,  the  shell's  handling of interrupt and terminate signals can be controlled with
       onintr, and its handling of hangups can be controlled with hup and nohup.

       The shell exits on a hangup (see also the logout shell variable).  By default, the  shell's  children
       do  too, but the shell does not send them a hangup when it exits.  hup arranges for the shell to send
       a hangup to a child when it exits, and nohup sets a child to ignore hangups.

   Terminal management (+)
       The shell uses three different sets of terminal (``tty'') modes: `edit', used when editing,  `quote',
       used  when  quoting literal characters, and `execute', used when executing commands.  The shell holds
       some settings in each mode constant, so commands which leave the tty  in  a  confused  state  do  not
       interfere  with  the shell.  The shell also matches changes in the speed and padding of the tty.  The
       list of tty modes that are kept constant can be examined and modified with the setty  builtin.   Note
       that  although  the editor uses CBREAK mode (or its equivalent), it takes typed-ahead characters any-way. anyway.

       The echotc, settc and telltc commands can be used to manipulate and debug terminal capabilities  from
       the command line.

       On  systems that support SIGWINCH or SIGWINDOW, the shell adapts to window resizing automatically and
       adjusts the environment variables LINES and COLUMNS if set.  If the environment variable TERMCAP con-tains contains
       tains li# and co# fields, the shell adjusts them to reflect the new window size.

       The  next sections of this manual describe all of the available Builtin commands, Special aliases and
       Special shell variables.

   Builtin commands
       %job    A synonym for the fg builtin command.

       %job &  A synonym for the bg builtin command.

       :       Does nothing, successfully.

       @ name = expr
       @ name[index] = expr
       @ name++|--@ name++|-@
       @ name[index]++|--The name[index]++|-The
               The first form prints the values of all shell variables.

               The second form assigns the value of expr to name.  The third form assigns the value of  expr
               to the index'th component of name; both name and its index'th component must already exist.

               expr may contain the operators `*', `+', etc., as in C.  If expr contains `<', `>', `&' or `'
               then at least that part of expr must be placed within `()'.  Note that the syntax of expr has
               nothing to do with that described under Expressions.

               The  fourth  and fifth forms increment (`++') or decrement (`--') name or its index'th compo-nent. component.

               The space between `@' and name is required.  The spaces between name and `=' and between  `='
               and expr are optional.  Components of expr must be separated by spaces.

       alias [name [wordlist]]
               Without  arguments, prints all aliases.  With name, prints the alias for name.  With name and
               wordlist, assigns wordlist as the alias of name.  wordlist is command  and  filename  substi-tuted. substituted.
               tuted.  name may not be `alias' or `unalias'.  See also the unalias builtin command.

       alloc   Shows  the amount of dynamic memory acquired, broken down into used and free memory.  With an
               argument shows the number of free and used blocks in  each  size  category.   The  categories
               start at size 8 and double at each step.  This command's output may vary across system types,
               because systems other than the VAX may use a different memory allocator.

       bg [%job ...]
               Puts the specified jobs (or, without arguments, the current job) into the background, contin-uing continuing
               uing  each if it is stopped.  job may be a number, a string, `', `%', `+' or `-' as described
               under Jobs.

       bindkey [-l|-d|-e|-v|-u] (+)
       bindkey [-a] [-b] [-k] [-r] [--] key (+)
       bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
               Without options, the first form lists all bound keys and the editor command to which each  is
               bound,  the  second  form  lists  the editor command to which key is bound and the third form
               binds the editor command command to key.  Options include:

               -l  Lists all editor commands and a short description of each.
               -d  Binds all keys to the standard bindings for the default editor.
               -e  Binds all keys to the standard GNU Emacs-like bindings.
               -v  Binds all keys to the standard vi(1)-like bindings.
               -a  Lists or changes key-bindings in the alternative key map.  This is the key map used in vi
                   command mode.
               -b  key  is interpreted as a control character written ^character (e.g., `^A') or C-character
                   (e.g., `C-A'), a meta character written M-character (e.g., `M-A'), a function key written
                   F-string (e.g., `F-string'), or an extended prefix key written X-character (e.g., `X-A').
               -k  key is interpreted as a symbolic arrow key name, which may be one of `down', `up', `left'
                   or `right'.
               -r  Removes key's binding.  Be careful: `bindkey -r' does not bind key to self-insert-command
                   (q.v.), it unbinds key completely.
               -c  command is interpreted as a builtin or external command instead of an editor command.
               -s  command is taken as a literal string and treated as terminal input  when  key  is  typed.
                   Bound  keys in command are themselves reinterpreted, and this continues for ten levels of
               --  Forces a break from option processing, so the next word is taken as key even if it begins
                   with '-'.
               -u (or any invalid option)
                   Prints a usage message.

               key  may  be  a  single  character or a string.  If a command is bound to a string, the first
               character of the string is bound to sequence-lead-in and the entire string is  bound  to  the

               Control characters in key can be literal (they can be typed by preceding them with the editor
               command quoted-insert, normally bound to `^V') or written caret-character style, e.g.,  `^A'.
               Delete  is  written  `^?'   (caret-question  mark).   key and command can contain backslashed
               escape sequences (in the style of System V echo(1)) as follows:

                   \a      Bell
                   \b      Backspace
                   \e      Escape
                   \f      Form feed
                   \n      Newline
                   \r      Carriage return
                   \t      Horizontal tab
                   \v      Vertical tab
                   \nnn    The ASCII character corresponding to the octal number nnn

               `\' nullifies the special meaning of the following character, if it has any, notably `\'  and

       bs2cmd bs2___-command (+)
               Passes  bs2___-command  to the BS2000 command interpreter for execution. Only non-interactive
               commands can be executed, and it is not possible to execute any command  that  would  overlay
               the image of the current process, like /EXECUTE or /CALL-PROCEDURE. (BS2000 only)

       break   Causes  execution  to  resume  after  the end of the nearest enclosing foreach or while.  The
               remaining commands on the current line are executed.  Multi-level breaks are thus possible by
               writing them all on one line.

       breaksw Causes a break from a switch, resuming after the endsw.

       builtins (+)
               Prints the names of all builtin commands.

       bye (+) A  synonym  for the logout builtin command.  Available only if the shell was so compiled; see
               the version shell variable.

       case label:
               A label in a switch statement as discussed below.

       cd [-p] [-l] [-n|-v] [name]
               If a directory name is given, changes the shell's working directory to name.  If not, changes
               to  home.  If name is `-' it is interpreted as the previous working directory (see Other sub-stitutions). substitutions).
               stitutions).  (+) If name is not a subdirectory of the current directory (and does not  begin
               with `/', `./' or `../'), each component of the variable cdpath is checked to see if it has a
               subdirectory name.  Finally, if all else fails but name  is  a  shell  variable  whose  value
               begins with `/', then this is tried to see if it is a directory.

               With  -p, prints the final directory stack, just like dirs.  The -l, -n and -v flags have the
               same effect on cd as on dirs, and they imply -p.  (+)

               See also the implicitcd shell variable.

       chdir   A synonym for the cd builtin command.

       complete [command [word/pattern/list[:select]/[[suffix]/] ...]] (+)
               Without arguments, lists all completions.  With command, lists completions for command.  With
               command and word etc., defines completions.

               command  may  be  a  full command name or a glob-pattern (see Filename substitution).  It can
               begin with `-' to indicate that completion should be used only when command is ambiguous.

               word specifies which word relative to the current word is to be completed, and may be one  of
               the following:

                   c   Current-word completion.  pattern is a glob-pattern which must match the beginning of
                       the current word on the command line.  pattern is ignored when completing the current
                   C   Like c, but includes pattern when completing the current word.
                   n   Next-word  completion.   pattern  is a glob-pattern which must match the beginning of
                       the previous word on the command line.
                   N   Like n, but must match the beginning of the word two before the current word.
                   p   Position-dependent completion.  pattern is a numeric range, with the same syntax used
                       to index shell variables, which must include the current word.

               list, the list of possible completions, may be one of the following:

                   a       Aliases
                   b       Bindings (editor commands)
                   c       Commands (builtin or external commands)
                   C       External commands which begin with the supplied path prefix
                   d       Directories
                   D       Directories which begin with the supplied path prefix
                   e       Environment variables
                   f       Filenames
                   F       Filenames which begin with the supplied path prefix
                   g       Groupnames
                   j       Jobs
                   l       Limits
                   n       Nothing
                   s       Shell variables
                   S       Signals
                   t       Plain (``text'') files
                   T       Plain (``text'') files which begin with the supplied path prefix
                   v       Any variables
                   u       Usernames
                   x       Like n, but prints select when list-choices is used.
                   X       Completions
                   $var    Words from the variable var
                   (...)   Words from the given list
                   `...`   Words from the output of command

               select  is  an  optional  glob-pattern.  If given, words from only list that match select are
               considered and the fignore shell variable is ignored.  The last three types of completion may
               not  have a select pattern, and x uses select as an explanatory message when the list-choices
               editor command is used.

               suffix is a single character to be appended to a successful completion.  If null, no  charac-ter character
               ter  is  appended.   If  omitted  (in which case the fourth delimiter can also be omitted), a
               slash is appended to directories and a space to other words.

               command invoked from `...` version has additional environment variable set, the variable name
               is  COMMAND_LINE  and contains (as its name indicates) contents of the current (already typed
               in) command line. One can examine and use contents of the COMMAND_LINE variable in her custom
               script  to  build  more sophisticated completions (see completion for svn(1) included in this

               Now for some examples.  Some commands take only directories as arguments, so there's no point
               completing plain files.

                   > complete cd 'p/1/d/'

               completes only the first word following `cd' (`p/1') with a directory.  p-type completion can
               also be used to narrow down command completion:

                   > co[^D]
                   complete compress
                   > complete -co* 'p/0/(compress)/'
                   > co[^D]
                   > compress

               This completion completes commands (words in position 0, `p/0') which begin with  `co'  (thus
               matching  `co*')  to  `compress' (the only word in the list).  The leading `-' indicates that
               this completion is to be used with only ambiguous commands.

                   > complete find 'n/-user/u/'

               is an example of n-type completion.  Any word  following  `find'  and  immediately  following
               `-user' is completed from the list of users.

                   > complete cc 'c/-I/d/'

               demonstrates c-type completion.  Any word following `cc' and beginning with `-I' is completed
               as a directory.  `-I' is not taken as part of the directory because we used lowercase c.

               Different lists are useful with different commands.

                   > complete alias 'p/1/a/'
                   > complete man 'p/*/c/'
                   > complete set 'p/1/s/'
                   > complete true 'p/1/x:Truth has no options./'

               These complete words following `alias' with aliases, `man'  with  commands,  and  `set'  with
               shell  variables.   `true'  doesn't  have  any  options, so x does nothing when completion is
               attempted and prints `Truth has no options.' when completion choices are listed.

               Note that the man example, and several other examples below, could just  as  well  have  used
               'c/*' or 'n/*' as 'p/*'.

               Words can be completed from a variable evaluated at completion time,

                   > complete ftp 'p/1/$hostnames/'
                   > set hostnames = (
                   > ftp [^D]
                   > ftp [^C]
                   > set hostnames = (
                   > ftp [^D]

               or from a command run at completion time:

                   > complete kill 'p/*/`ps | awk \{print\ \$1\}`/'
                   > kill -9 [^D]
                   23113 23377 23380 23406 23429 23529 23530 PID

               Note  that the complete command does not itself quote its arguments, so the braces, space and
               `$' in `{print $1}' must be quoted explicitly.

               One command can have multiple completions:

                   > complete dbx 'p/2/(core)/' 'p/*/c/'

               completes the second argument to `dbx' with the word `core' and all other arguments with com-mands. commands.
               mands.   Note  that  the  positional completion is specified before the next-word completion.
               Because completions are evaluated from left to right, if the next-word completion were speci-fied specified
               fied first it would always match and the positional completion would never be executed.  This
               is a common mistake when defining a completion.

               The select pattern is useful when a command takes files with only particular forms  as  argu-ments. arguments.
               ments.  For example,

                   > complete cc 'p/*/f:*.[cao]/'

               completes  `cc'  arguments  to  files  ending  in  only `.c', `.a', or `.o'.  select can also
               exclude files, using negation of a glob-pattern as  described  under  Filename  substitution.
               One might use

                   > complete rm 'p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/'

               to  exclude  precious  source  code  from  `rm'  completion.  Of course, one could still type
               excluded names manually or override the completion mechanism using the  complete-word-raw  or
               list-choices-raw editor commands (q.v.).

               The `C', `D', `F' and `T' lists are like `c', `d', `f' and `t' respectively, but they use the
               select argument in a different way: to restrict completion to files beginning with a particu-lar particular
               lar  path  prefix.   For  example, the Elm mail program uses `=' as an abbreviation for one's
               mail directory.  One might use

                   > complete elm c@=@F:$HOME/Mail/@

               to complete `elm -f =' as if it were `elm -f ~/Mail/'.  Note that we used `@' instead of  `/'
               to  avoid confusion with the select argument, and we used `$HOME' instead of `~' because home
               directory substitution works at only the beginning of a word.

               suffix is used to add a nonstandard suffix (not space or `/' for  directories)  to  completed

                   > complete finger 'c/*@/$hostnames/' 'p/1/u/@'

               completes  arguments  to  `finger' from the list of users, appends an `@', and then completes
               after the `@' from the `hostnames' variable.  Note again the order in which  the  completions
               are specified.

               Finally, here's a complex example for inspiration:

                   > complete find \
                   'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \
                   'n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \
                   'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \
                   'n/-type/(b c d f l p s)/' \
                   'c/-/(name newer cpio ncpio exec ok user \
                   group fstype type atime ctime depth inum \
                   ls mtime nogroup nouser perm print prune \
                   size xdev)/' \

               This  completes words following `-name', `-newer', `-cpio' or `ncpio' (note the pattern which
               matches both) to files, words following `-exec' or `-ok' to commands, words following  `user'
               and `group' to users and groups respectively and words following `-fstype' or `-type' to mem-bers members
               bers of the given lists.  It also completes the switches themselves from the given list (note
               the  use of c-type completion) and completes anything not otherwise completed to a directory.

               Remember that programmed completions are ignored if the word being completed is a tilde  sub-stitution substitution
               stitution (beginning with `~') or a variable (beginning with `$').  complete is an experimen-tal experimental
               tal feature, and the syntax may change in future versions of the shell.  See also the  uncom-plete uncomplete
               plete builtin command.

               Continues  execution  of the nearest enclosing while or foreach.  The rest of the commands on
               the current line are executed.

               Labels the default case in a switch statement.  It should come after all case labels.

       dirs [-l] [-n|-v]
       dirs -S|-L [filename] (+)
       dirs -c (+)
               The first form prints the directory stack.  The top of the stack is at the left and the first
               directory  in  the  stack is the current directory.  With -l, `~' or `~name' in the output is
               expanded explicitly to home or the pathname of the home directory for user  name.   (+)  With
               -n,  entries  are wrapped before they reach the edge of the screen.  (+) With -v, entries are
               printed one per line, preceded by their stack positions.  (+) If more than one of -n or -v is
               given, -v takes precedence.  -p is accepted but does nothing.

               With  -S,  the  second form saves the directory stack to filename as a series of cd and pushd
               commands.  With -L, the shell sources filename, which is presumably a  directory  stack  file
               saved  by the -S option or the savedirs mechanism.  In either case, dirsfile is used if file-name filename
               name is not given and ~/.cshdirs is used if dirsfile is unset.

               Note that login shells do the equivalent of `dirs -L' on startup and,  if  savedirs  is  set,
               `dirs  -S'  before  exiting.   Because  only ~/.tcshrc is normally sourced before ~/.cshdirs,
               dirsfile should be set in ~/.tcshrc rather than ~/.login.

               The last form clears the directory stack.

       echo [-n] word ...
               Writes each word to the shell's standard output, separated by spaces and  terminated  with  a
               newline.   The  echo_style shell variable may be set to emulate (or not) the flags and escape
               sequences of the BSD and/or System V versions of echo; see echo(1).

       echotc [-sv] arg ... (+)
               Exercises the terminal capabilities (see termcap(5)) in args.   For  example,  'echotc  home'
               sends  the cursor to the home position, 'echotc cm 3 10' sends it to column 3 and row 10, and
               'echotc ts 0; echo "This is a test."; echotc fs' prints "This is  a  test."   in  the  status

               If  arg  is  'baud',  'cols',  'lines', 'meta' or 'tabs', prints the value of that capability
               ("yes" or "no" indicating that the terminal does or does  not  have  that  capability).   One
               might  use  this  to  make  the output from a shell script less verbose on slow terminals, or
               limit command output to the number of lines on the screen:

                   > set history=`echotc lines`
                   > @ history--Termcap history-Termcap

               Termcap strings may contain wildcards which will not echo correctly.  One should  use  double
               quotes  when  setting  a  shell variable to a terminal capability string, as in the following
               example that places the date in the status line:

                   > set tosl="`echotc ts 0`"
                   > set frsl="`echotc fs`"
                   > echo -n "$tosl";date; echo -n "$frsl"

               With -s, nonexistent capabilities return the empty string rather than causing an error.  With
               -v, messages are verbose.

       endsw   See the description of the foreach, if, switch, and while statements below.

       eval arg ...
               Treats  the arguments as input to the shell and executes the resulting command(s) in the con-text context
               text of the current shell.  This is usually used to execute commands generated as the  result
               of  command or variable substitution, because parsing occurs before these substitutions.  See
               tset(1) for a sample use of eval.

       exec command
               Executes the specified command in place of the current shell.

       exit [expr]
               The shell exits either with the value of the specified  expr  (an  expression,  as  described
               under Expressions) or, without expr, with the value 0.

       fg [%job ...]
               Brings  the specified jobs (or, without arguments, the current job) into the foreground, con-tinuing continuing
               tinuing each if it is stopped.  job may be a number,  a  string,  `',  `%',  `+'  or  `-'  as
               described under Jobs.  See also the run-fg-editor editor command.

       filetest -op file ... (+)
               Applies  op  (which  is a file inquiry operator as described under File inquiry operators) to
               each file and returns the results as a space-separated list.

       foreach name (wordlist)
       end     Successively sets the variable name to each member of wordlist and executes the  sequence  of
               commands  between this command and the matching end.  (Both foreach and end must appear alone
               on separate lines.)  The builtin command continue may be used to  continue  the  loop  prema-turely prematurely
               turely  and the builtin command break to terminate it prematurely.  When this command is read
               from the terminal, the loop is read once prompting with `foreach? ' (or prompt2)  before  any
               statements  in the loop are executed.  If you make a mistake typing in a loop at the terminal
               you can rub it out.

       getspath (+)
               Prints the system execution path.  (TCF only)

       getxvers (+)
               Prints the experimental version prefix.  (TCF only)

       glob wordlist
               Like echo, but the `-n' parameter is not recognized and words are delimited by  null  charac-ters characters
               ters  in  the  output.   Useful for programs which wish to use the shell to filename expand a
               list of words.

       goto word
               word is filename and command-substituted to yield a string of the form  `label'.   The  shell
               rewinds  its  input  as  much as possible, searches for a line of the form `label:', possibly
               preceded by blanks or tabs, and continues execution after that line.

               Prints a statistics line indicating how effective the internal hash table has been at  locat-ing locating
               ing  commands  (and  avoiding  exec's).   An exec is attempted for each component of the path
               where the hash function indicates a possible hit, and in each component which does not  begin
               with a `/'.

               On machines without vfork(2), prints only the number and size of hash buckets.

       history [-hTr] [n]
       history -S|-L|-M [filename] (+)
       history -c (+)
               The  first  form  prints the history event list.  If n is given only the n most recent events
               are printed or saved.  With -h, the history list is printed without leading numbers.   If  -T
               is  specified,  timestamps  are  printed  also in comment form.  (This can be used to produce
               files suitable for loading with 'history -L' or 'source -h'.)  With -r, the order of printing
               is most recent first rather than oldest first.

               With  -S, the second form saves the history list to filename.  If the first word of the save-hist savehist
               hist shell variable is set to a number, at most that many lines are  saved.   If  the  second
               word of savehist is set to `merge', the history list is merged with the existing history file
               instead of replacing it (if there is one) and sorted by time stamp.  (+) Merging is  intended
               for  an  environment  like the X Window System with several shells in simultaneous use.  Cur-rently Currently
               rently it succeeds only when the shells quit nicely one after another.

               With -L, the shell appends filename, which is presumably a  history  list  saved  by  the  -S
               option  or  the  savehist mechanism, to the history list.  -M is like -L, but the contents of
               filename are merged into the history list and sorted by timestamp.  In either case,  histfile
               is  used  if filename is not given and ~/.history is used if histfile is unset.  `history -L'
               is exactly like 'source -h' except that it does not require a filename.

               Note that login shells do the equivalent of `history -L' on startup and, if savehist is  set,
               `history  -S'  before exiting.  Because only ~/.tcshrc is normally sourced before ~/.history,
               histfile should be set in ~/.tcshrc rather than ~/.login.

               If histlit is set, the first and second forms print and save the literal (unexpanded) form of
               the history list.

               The last form clears the history list.

       hup [command] (+)
               With  command,  runs  command  such that it will exit on a hangup signal and arranges for the
               shell to send it a hangup signal when the shell exits.  Note that commands may set their  own
               response  to  hangups, overriding hup.  Without an argument (allowed in only a shell script),
               causes the shell to exit on a hangup for the remainder of the script.  See also  Signal  han-dling handling
               dling and the nohup builtin command.

       if (expr) command
               If  expr (an expression, as described under Expressions) evaluates true, then command is exe-cuted. executed.
               cuted.  Variable substitution on command happens early, at the same time it does for the rest
               of  the  if  command.   command must be a simple command, not an alias, a pipeline, a command
               list or a parenthesized command list, but it may have  arguments.   Input/output  redirection
               occurs even if expr is false and command is thus not executed; this is a bug.

       if (expr) then
       else if (expr2) then
       endif   If  the specified expr is true then the commands to the first else are executed; otherwise if
               expr2 is true then the commands to the second else are executed, etc.  Any number of  else-if
               pairs  are  possible;  only  one  endif is needed.  The else part is likewise optional.  (The
               words else and endif must appear at the beginning of input lines; the if must appear alone on
               its input line or after an else.)

       inlib shared-library ... (+)
               Adds  each  shared-library  to  the  current environment.  There is no way to remove a shared
               library.  (Domain/OS only)

       jobs [-l]
               Lists the active jobs.  With -l, lists process IDs in addition to the normal information.  On
               TCF systems, prints the site on which each job is executing.

       kill [-s signal] %job|pid ...
       kill -l The first and second forms sends the specified signal (or, if none is given, the TERM (termi-nate) (terminate)
               nate) signal) to the specified jobs or processes.  job may be a number, a  string,  `',  `%',
               `+'  or `-' as described under Jobs.  Signals are either given by number or by name (as given
               in /usr/include/signal.h, stripped of the prefix `SIG').  There is  no  default  job;  saying
               just  `kill'  does  not  send  a signal to the current job.  If the signal being sent is TERM
               (terminate) or HUP (hangup), then the job or process is sent  a  CONT  (continue)  signal  as
               well.  The third form lists the signal names.

       limit [-h] [resource [maximum-use]]
               Limits the consumption by the current process and each process it creates to not individually
               exceed maximum-use on the specified resource.  If no maximum-use is given, then  the  current
               limit is printed; if no resource is given, then all limitations are given.  If the -h flag is
               given, the hard limits are used instead of the current limits.   The  hard  limits  impose  a
               ceiling  on the values of the current limits.  Only the super-user may raise the hard limits,
               but a user may lower or raise the current limits within the legal range.

               Controllable resources currently include (if supported by the OS):

                      the maximum number of cpu-seconds to be used by each process

                      the largest single file which can be created

                      the maximum growth of the data+stack region via sbrk(2) beyond the end of the  program

                      the maximum size of the automatically-extended stack region

                      the size of the largest core dump that will be created

                      the  maximum  amount  of physical memory a process may have allocated to it at a given

                      the maximum amount of memory a process may allocate per brk() system call

               descriptors or openfiles
                      the maximum number of open files for this process

                      the maximum number of threads for this process

                      the maximum size which a process may lock into memory using mlock(2)

                      the maximum number of simultaneous processes for this user id

               sbsize the maximum size of socket buffer usage for this user

                      the maximum amount of swap space reserved or used for this user

               maximum-use may be given as a (floating point or integer) number followed by a scale  factor.
               For  all  limits  other  than cputime the default scale is `k' or `kilobytes' (1024 bytes); a
               scale factor of `m' or `megabytes' may also be used.  For  cputime  the  default  scaling  is
               `seconds',  while `m' for minutes or `h' for hours, or a time of the form `mm:ss' giving min-utes minutes
               utes and seconds may be used.

               For both resource names and scale factors, unambiguous prefixes of the names suffice.

       log (+) Prints the watch shell variable and reports on each user indicated in watch who is logged in,
               regardless of when they last logged in.  See also watchlog.

       login   Terminates a login shell, replacing it with an instance of /bin/login. This is one way to log
               off, included for compatibility with sh(1).

       logout  Terminates a login shell.  Especially useful if ignoreeof is set.

       ls-F [-switch ...] [file ...] (+)
               Lists files like `ls -F', but much faster.  It identifies each type of special  file  in  the
               listing with a special character:

               /   Directory
               *   Executable
               #   Block device
               %   Character device
               |   Named pipe (systems with named pipes only)
               =   Socket (systems with sockets only)
               @   Symbolic link (systems with symbolic links only)
               +   Hidden directory (AIX only) or context dependent (HP/UX only)
               :   Network special (HP/UX only)

               If the listlinks shell variable is set, symbolic links are identified in more detail (on only
               systems that have them, of course):

               @   Symbolic link to a non-directory
               >   Symbolic link to a directory
               &   Symbolic link to nowhere

               listlinks also slows down ls-F and causes partitions holding files  pointed  to  by  symbolic
               links to be mounted.

               If  the listflags shell variable is set to `x', `a' or `A', or any combination thereof (e.g.,
               `xA'), they are used as flags to ls-F, making it act like `ls -xF', `ls -Fa', `ls -FA'  or  a
               combination  (e.g., `ls -FxA').  On machines where `ls -C' is not the default, ls-F acts like
               `ls -CF', unless listflags contains an `x', in which case it acts like `ls -xF'.  ls-F passes
               its  arguments  to  ls(1)  if it is given any switches, so `alias ls ls-F' generally does the
               right thing.

               The ls-F builtin can list files using different colors depending on the  filetype  or  exten-sion. extension.
               sion.  See the color tcsh variable and the LS_COLORS environment variable.

       migrate [-site] pid|%jobid ... (+)
       migrate -site (+)
               The  first  form migrates the process or job to the site specified or the default site deter-mined determined
               mined by the system path.  The second form is equivalent to `migrate -site $$':  it  migrates
               the  current  process to the specified site.  Migrating the shell itself can cause unexpected
               behavior, because the shell does not like to lose its tty.  (TCF only)

       newgrp [-] group (+)
               Equivalent to `exec newgrp'; see newgrp(1).  Available only if the shell was so compiled; see
               the version shell variable.

       nice [+number] [command]
               Sets  the  scheduling  priority for the shell to number, or, without number, to 4.  With com-mand, command,
               mand, runs command at the appropriate priority.  The greater the number,  the  less  cpu  the
               process  gets.   The  super-user  may  specify negative priority by using `nice -number ...'.
               Command is always executed in a sub-shell, and the restrictions placed on commands in  simple
               if statements apply.

       nohup [command]
               With  command,  runs command such that it will ignore hangup signals.  Note that commands may
               set their own response to hangups, overriding nohup.  Without an argument (allowed in only  a
               shell  script), causes the shell to ignore hangups for the remainder of the script.  See also
               Signal handling and the hup builtin command.

       notify [%job ...]
               Causes the shell to notify the user asynchronously when the status of any  of  the  specified
               jobs (or, without %job, the current job) changes, instead of waiting until the next prompt as
               is usual.  job may be a number, a string, `', `%', `+' or `-' as described under  Jobs.   See
               also the notify shell variable.

       onintr [-|label]
               Controls  the  action  of  the  shell on interrupts.  Without arguments, restores the default
               action of the shell on interrupts, which is to terminate shell scripts or to  return  to  the
               terminal  command  input  level.  With `-', causes all interrupts to be ignored.  With label,
               causes the shell to execute a `goto label' when an interrupt is received or a  child  process
               terminates because it was interrupted.

               onintr  is  ignored if the shell is running detached and in system startup files (see FILES),
               where interrupts are disabled anyway.

       popd [-p] [-l] [-n|-v] [+n]
               Without arguments, pops the directory stack and returns to the new  top  directory.   With  a
               number `+n', discards the n'th entry in the stack.

               Finally,  all forms of popd print the final directory stack, just like dirs.  The pushdsilent
               shell variable can be set to prevent this and the -p flag can be given to  override  pushdsi-lent. pushdsilent.
               lent.  The -l, -n and -v flags have the same effect on popd as on dirs.  (+)

       printenv [name] (+)
               Prints  the  names  and  values  of all environment variables or, with name, the value of the
               environment variable name.

       pushd [-p] [-l] [-n|-v] [name|+n]
               Without arguments, exchanges the top two elements of the directory stack.  If pushdtohome  is
               set,  pushd  without  arguments  does  `pushd ~', like cd.  (+) With name, pushes the current
               working directory onto the directory stack and changes to name.  If name is `-' it is  inter-preted interpreted
               preted as the previous working directory (see Filename substitution).  (+) If dunique is set,
               pushd removes any instances of name from the stack before pushing it  onto  the  stack.   (+)
               With  a number `+n', rotates the nth element of the directory stack around to be the top ele-ment element
               ment and changes to it.  If dextract is set, however, `pushd +n' extracts the nth  directory,
               pushes it onto the top of the stack and changes to it.  (+)

               Finally, all forms of pushd print the final directory stack, just like dirs.  The pushdsilent
               shell variable can be set to prevent this and the -p flag can be given to  override  pushdsi-lent. pushdsilent.
               lent.  The -l, -n and -v flags have the same effect on pushd as on dirs.  (+)

       rehash  Causes  the internal hash table of the contents of the directories in the path variable to be
               recomputed.  This is needed if new commands are added to directories in path  while  you  are
               logged in.  This should be necessary only if you add commands to one of your own directories,
               or if a systems programmer changes the contents of  one  of  the  system  directories.   Also
               flushes the cache of home directories built by tilde expansion.

       repeat count command
               The  specified  command,  which is subject to the same restrictions as the command in the one
               line if statement above, is executed count times.  I/O redirections occur exactly once,  even
               if count is 0.

       rootnode //nodename (+)
               Changes  the  rootnode  to  //nodename,  so  that  `/'  will  be interpreted as `//nodename'.
               (Domain/OS only)

       sched (+)
       sched [+]hh:mm command (+)
       sched -n (+)
               The first form prints the scheduled-event list.  The sched  shell  variable  may  be  set  to
               define the format in which the scheduled-event list is printed.  The second form adds command
               to the scheduled-event list.  For example,

                   > sched 11:00 echo It\'s eleven o\'clock.

               causes the shell to echo `It's eleven o'clock.' at 11 AM.  The time may be in  12-hour  AM/PM

                   > sched 5pm set prompt='[%h] It\'s after 5; go home: >'

               or may be relative to the current time:

                   > sched +2:15 /usr/lib/uucp/uucico -r1 -sother

               A  relative  time specification may not use AM/PM format.  The third form removes item n from
               the event list:

                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
                        2  Wed Apr  4 17:00  set prompt=[%h] It's after 5; go home: >
                   > sched -2
                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother

               A command in the scheduled-event list is executed just before the  first  prompt  is  printed
               after the time when the command is scheduled.  It is possible to miss the exact time when the
               command is to be run, but an overdue command will execute at  the  next  prompt.   A  command
               which  comes due while the shell is waiting for user input is executed immediately.  However,
               normal operation of an already-running command will not be interrupted so that  a  scheduled-event scheduledevent
               event list element may be run.

               This  mechanism  is  similar to, but not the same as, the at(1) command on some Unix systems.
               Its major disadvantage is that it may not run a command at exactly the specified  time.   Its
               major  advantage  is  that because sched runs directly from the shell, it has access to shell
               variables and other structures.  This provides a mechanism for changing one's  working  envi-ronment environment
               ronment based on the time of day.

       set name ...
       set name=word ...
       set [-r] [-f|-l] name=(wordlist) ... (+)
       set name[index]=word ...
       set -r (+)
       set -r name ... (+)
       set -r name=word ... (+)
               The  first form of the command prints the value of all shell variables.  Variables which con-tain contain
               tain more than a single word print as a parenthesized word list.  The second form  sets  name
               to  the null string.  The third form sets name to the single word.  The fourth form sets name
               to the list of words in wordlist.  In all cases the value is command and  filename  expanded.
               If  -r  is specified, the value is set read-only.  If -f or -l are specified, set only unique
               words keeping their order.  -f prefers the first occurrence of a word, and -l the last.   The
               fifth  form  sets  the index'th component of name to word; this component must already exist.
               The sixth form lists only the names of all shell variables that are read-only.   The  seventh
               form  makes  name read-only, whether or not it has a value.  The second form sets name to the
               null string.  The eighth form is the same as the third form, but make name read-only  at  the
               same time.

               These  arguments  can be repeated to set and/or make read-only multiple variables in a single
               set command.  Note, however, that variable expansion happens for  all  arguments  before  any
               setting  occurs.   Note also that `=' can be adjacent to both name and word or separated from
               both by whitespace, but cannot be adjacent to only one or the  other.   See  also  the  unset
               builtin command.

       setenv [name [value]]
               Without  arguments,  prints  the  names and values of all environment variables.  Given name,
               sets the environment variable name to value or, without value, to the null string.

       setpath path (+)
               Equivalent to setpath(1).  (Mach only)

       setspath LOCAL|site|cpu ... (+)
               Sets the system execution path.  (TCF only)

       settc cap value (+)
               Tells the shell to believe that the terminal capability cap (as defined  in  termcap(5))  has
               the  value  value.  No sanity checking is done.  Concept terminal users may have to `settc xn
               no' to get proper wrapping at the rightmost column.

       setty [-d|-q|-x] [-a] [[+|-]mode] (+)
               Controls which tty modes (see Terminal management) the shell does not allow to  change.   -d,
               -q  or  -x  tells  setty  to act on the `edit', `quote' or `execute' set of tty modes respec-tively; respectively;
               tively; without -d, -q or -x, `execute' is used.

               Without other arguments, setty lists the modes in the chosen set which are fixed on (`+mode')
               or  off  (`-mode').   The  available modes, and thus the display, vary from system to system.
               With -a, lists all tty modes in the chosen set whether or not they are  fixed.   With  +mode,
               -mode  or  mode,  fixes  mode  on or off or removes control from mode in the chosen set.  For
               example, `setty +echok echoe' fixes `echok' mode on and allows commands to turn `echoe'  mode
               on or off, both when the shell is executing commands.

       setxvers [string] (+)
               Set  the  experimental  version  prefix  to string, or removes it if string is omitted.  (TCF

       shift [variable]
               Without arguments, discards argv[1] and shifts the members of argv to the  left.   It  is  an
               error for argv not to be set or to have less than one word as value.  With variable, performs
               the same function on variable.

       source [-h] name [args ...]
               The shell reads and executes commands from name.  The commands are not placed on the  history
               list.  If any args are given, they are placed in argv.  (+) source commands may be nested; if
               they are nested too deeply the shell may run out of file descriptors.  An error in  a  source
               at any level terminates all nested source commands.  With -h, commands are placed on the his-tory history
               tory list instead of being executed, much like `history -L'.

       stop %job|pid ...
               Stops the specified jobs or processes which are executing in the background.  job  may  be  a
               number, a string, `', `%', `+' or `-' as described under Jobs.  There is no default job; say-ing saying
               ing just `stop' does not stop the current job.

       suspend Causes the shell to stop in its tracks, much as if it had been sent a stop  signal  with  ^Z.
               This is most often used to stop shells started by su(1).

       switch (string)
       case str1:
       endsw   Each  case label is successively matched, against the specified string which is first command
               and filename expanded.  The file metacharacters `*', `?' and `[...]'  may be used in the case
               labels, which are variable expanded.  If none of the labels match before a `default' label is
               found, then the execution begins after the default label.  Each case label  and  the  default
               label  must  appear at the beginning of a line.  The command breaksw causes execution to con-tinue continue
               tinue after the endsw.  Otherwise control may fall through case labels and default labels  as
               in C.  If no label matches and there is no default, execution continues after the endsw.

       telltc (+)
               Lists the values of all terminal capabilities (see termcap(5)).

       termname [terminal type] (+)
               Tests  if  terminal  type  (or the current value of TERM if no terminal type is given) has an
               entry in the hosts termcap(5) or terminfo(5) database. Prints the terminal type to stdout and
               returns 0 if an entry is present otherwise returns 1.

       time [command]
               Executes command (which must be a simple command, not an alias, a pipeline, a command list or
               a parenthesized command list) and prints a time summary as described under the time variable.
               If  necessary,  an  extra  shell is created to print the time statistic when the command com-pletes. completes.
               pletes.  Without command, prints a time summary for the current shell and its children.

       umask [value]
               Sets the file creation mask to value, which is given in octal.  Common values  for  the  mask
               are  002, giving all access to the group and read and execute access to others, and 022, giv-ing giving
               ing read and execute access to the group and others.  Without value, prints the current  file
               creation mask.

       unalias pattern
               Removes  all aliases whose names match pattern.  `unalias *' thus removes all aliases.  It is
               not an error for nothing to be unaliased.

       uncomplete pattern (+)
               Removes all completions whose names match pattern.  `uncomplete *' thus removes  all  comple-tions. completions.
               tions.  It is not an error for nothing to be uncompleted.

       unhash  Disables use of the internal hash table to speed location of executed programs.

       universe universe (+)
               Sets the universe to universe.  (Masscomp/RTU only)

       unlimit [-hf] [resource]
               Removes the limitation on resource or, if no resource is specified, all resource limitations.
               With -h, the corresponding hard limits are removed.  Only the super-user may do  this.   Note
               that  unlimit  may  not  exit  successful,  since most systems do not allow descriptors to be
               unlimited.  With -f errors are ignored.

       unset pattern
               Removes all variables whose names match pattern, unless they are read-only.  `unset  *'  thus
               removes  all variables unless they are read-only; this is a bad idea.  It is not an error for
               nothing to be unset.

       unsetenv pattern
               Removes all environment variables whose names match pattern.  `unsetenv *' thus  removes  all
               environment  variables; this is a bad idea.  It is not an error for nothing to be unsetenved.

       ver [systype [command]] (+)
               Without arguments, prints SYSTYPE.  With systype, sets SYSTYPE to systype.  With systype  and
               command,  executes  command  under systype.  systype may be `bsd4.3' or `sys5.3'.  (Domain/OS

       wait    The shell waits for all background jobs.  If the shell is interactive, an interrupt will dis-rupt disrupt
               rupt the wait and cause the shell to print the names and job numbers of all outstanding jobs.

       warp universe (+)
               Sets the universe to universe.  (Convex/OS only)

       watchlog (+)
               An alternate name for the log builtin command (q.v.).  Available only if  the  shell  was  so
               compiled; see the version shell variable.

       where command (+)
               Reports  all known instances of command, including aliases, builtins and executables in path.

       which command (+)
               Displays the command that will be executed by the shell after substitutions, path  searching,
               etc.   The  builtin  command is just like which(1), but it correctly reports tcsh aliases and
               builtins and is 10 to 100 times faster.  See also the which-command editor command.

       while (expr)
       end     Executes the commands between the while and the matching end while expr  (an  expression,  as
               described  under  Expressions)  evaluates non-zero.  while and end must appear alone on their
               input lines.  break and continue may be used to terminate or continue the  loop  prematurely.
               If  the  input  is  a  terminal, the user is prompted the first time through the loop as with

   Special aliases (+)
       If set, each of these aliases executes automatically at the indicated time.  They are  all  initially

       beepcmd Runs when the shell wants to ring the terminal bell.

       cwdcmd  Runs  after  every  change of working directory.  For example, if the user is working on an X
               window system using xterm(1) and a re-parenting window manager that supports title bars  such
               as twm(1) and does

                   > alias cwdcmd  'echo -n "^[]2;${HOST}:$cwd ^G"'

               then  the  shell  will change the title of the running xterm(1) to be the name of the host, a
               colon, and the full current working directory.  A fancier way to do that is

                   > alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'

               This will put the hostname and working directory on the title bar but only  the  hostname  in
               the icon manager menu.

               Note  that  putting  a  cd,  pushd  or  popd in cwdcmd may cause an infinite loop.  It is the
               author's opinion that anyone doing so will get what they deserve.

       jobcmd  Runs before each command gets executed, or when the command changes state.  This  is  similar
               to postcmd, but it does not print builtins.

                   > alias jobcmd  'echo -n "^[]2\;\!#:q^G"'

               then executing vi foo.c will put the command string in the xterm title bar.

               Invoked  by the run-help editor command.  The command name for which help is sought is passed
               as sole argument.  For example, if one does

                   > alias helpcommand '\!:1 --help'

               then the help display of the command itself will be invoked, using the GNU help calling  con-vention. convention.
               vention.   Currently  there  is no easy way to account for various calling conventions (e.g.,
               the customary Unix `-h'), except by using a table of many commands.

               Runs every tperiod minutes.  This provides a convenient means  for  checking  on  common  but
               infrequent changes such as new mail.  For example, if one does

                   > set tperiod = 30
                   > alias periodic checknews

               then the checknews(1) program runs every 30 minutes.  If periodic is set but tperiod is unset
               or set to 0, periodic behaves like precmd.

       precmd  Runs just before each prompt is printed.  For example, if one does

                   > alias precmd date

               then date(1) runs just before the shell prompts for each command.  There  are  no  limits  on
               what precmd can be set to do, but discretion should be used.

       postcmd Runs before each command gets executed.

                   > alias postcmd  'echo -n "^[]2\;\!#:q^G"'

               then executing vi foo.c will put the command string in the xterm title bar.

       shell   Specifies  the  interpreter  for executable scripts which do not themselves specify an inter-preter. interpreter.
               preter.  The first word should be  a  full  path  name  to  the  desired  interpreter  (e.g.,
               `/bin/csh' or `/usr/local/bin/tcsh').

   Special shell variables
       The variables described in this section have special meaning to the shell.

       The  shell sets addsuffix, argv, autologout, csubstnonl, command, echo_style, edit, gid, group, home,
       loginsh, oid, path, prompt, prompt2, prompt3, shell, shlvl, tcsh, term, tty, uid, user and version at
       startup;  they do not change thereafter unless changed by the user.  The shell updates cwd, dirstack,
       owd and status when necessary, and sets logout on logout.

       The shell synchronizes group, home, path, shlvl, term and user with the environment variables of  the
       same names: whenever the environment variable changes the shell changes the corresponding shell vari-able variable
       able to match (unless the shell variable is read-only) and vice versa.  Note that  although  cwd  and
       PWD  have  identical meanings, they are not synchronized in this manner, and that the shell automati-cally automatically
       cally interconverts the different formats of path and PATH.

       addsuffix (+)
               If set, filename completion adds `/' to the end of directories and a space to the end of nor-mal normal
               mal files when they are matched exactly.  Set by default.

       afsuser (+)
               If  set,  autologout's autolock feature uses its value instead of the local username for ker-beros kerberos
               beros authentication.

       ampm (+)
               If set, all times are shown in 12-hour AM/PM format.

       argv    The arguments to the shell.  Positional  parameters  are  taken  from  argv,  i.e.,  `$1'  is
               replaced by `$argv[1]', etc.  Set by default, but usually empty in interactive shells.

       autocorrect (+)
               If  set,  the  spell-word  editor  command  is  invoked  automatically before each completion

       autoexpand (+)
               If set, the expand-history editor command is invoked  automatically  before  each  completion
               attempt.  If this is set to onlyhistory, then only history will be expanded and a second com-pletion completion
               pletion will expand filenames.

       autolist (+)
               If set, possibilities are listed after an ambiguous completion.  If set to `ambiguous',  pos-sibilities possibilities
               sibilities are listed only when no new characters are added by completion.

       autologout (+)
               The  first word is the number of minutes of inactivity before automatic logout.  The optional
               second word is the number of minutes of inactivity before automatic locking.  When the  shell
               automatically  logs out, it prints `auto-logout', sets the variable logout to `automatic' and
               exits.  When the shell automatically locks, the user is required to  enter  his  password  to
               continue  working.   Five  incorrect attempts result in automatic logout.  Set to `60' (auto-matic (automatic
               matic logout after 60 minutes, and no locking) by default in login and superuser shells,  but
               not  if  the  shell thinks it is running under a window system (i.e., the DISPLAY environment
               variable is set), the tty is a pseudo-tty (pty) or the shell was not  so  compiled  (see  the
               version shell variable).  See also the afsuser and logout shell variables.

       backslash_quote (+)
               If  set,  backslashes  (`\')  always  quote `\', `'', and `"'.  This may make complex quoting
               tasks easier, but it can cause syntax errors in csh(1) scripts.

       catalog The file name of the message catalog.  If set, tcsh use `tcsh.${catalog}' as a message  cata-log catalog
               log instead of default `tcsh'.

       cdpath  A  list  of  directories in which cd should search for subdirectories if they aren't found in
               the current directory.

       color   If set, it enables color display for the builtin ls-F  and  it  passes  --color=auto  to  ls.
               Alternatively,  it  can  be  set to only ls-F or only ls to enable color to only one command.
               Setting it to nothing is equivalent to setting it to (ls-F ls).

               If set, it enables color escape sequence for NLS message files.   And  display  colorful  NLS

       command (+)
               If set, the command which was passed to the shell with the -c flag (q.v.).

       compat_expr (+)
               If set, the shell will evaluate expressions right to left, like the original csh.

       complete (+)
               If  set to `enhance', completion 1) ignores case and 2) considers periods, hyphens and under-scores underscores
               scores (`.', `-' and `_') to be word separators and hyphens and underscores to be equivalent.
               If set to `igncase', the completion becomes case insensitive.

       continue (+)
               If  set to a list of commands, the shell will continue the listed commands, instead of start-ing starting
               ing a new one.

       continue_args (+)
               Same as continue, but the shell will execute:

                   echo `pwd` $argv > ~/.<cmd>_pause; %<cmd>

       correct (+)
               If set to `cmd', commands are automatically spelling-corrected.  If set to  `complete',  com-mands commands
               mands are automatically completed.  If set to `all', the entire command line is corrected.

       csubstnonl (+)
               If set, newlines and carriage returns in command substitution are replaced by spaces.  Set by

       cwd     The full pathname of the current directory.  See also the dirstack and owd shell variables.

       dextract (+)
               If set, `pushd +n' extracts the nth directory from the directory stack rather  than  rotating
               it to the top.

       dirsfile (+)
               The  default  location  in  which `dirs -S' and `dirs -L' look for a history file.  If unset,
               ~/.cshdirs is used.  Because only ~/.tcshrc is normally sourced before  ~/.cshdirs,  dirsfile
               should be set in ~/.tcshrc rather than ~/.login.

       dirstack (+)
               An  array of all the directories on the directory stack.  `$dirstack[1]' is the current work-ing working
               ing directory, `$dirstack[2]' the first directory on the stack, etc.  Note that  the  current
               working  directory is `$dirstack[1]' but `=0' in directory stack substitutions, etc.  One can
               change the stack arbitrarily by setting dirstack, but the first element (the current  working
               directory) is always correct.  See also the cwd and owd shell variables.

       dspmbyte (+)
               Has  an  affect iff 'dspm' is listed as part of the version shell variable.  If set to `euc',
               it enables display and editing EUC-kanji(Japanese) code.  If set to `sjis', it  enables  dis-play display
               play  and editing Shift-JIS(Japanese) code.  If set to `big5', it enables display and editing
               Big5(Chinese) code.  If set to `utf8', it enables display and editing Utf8(Unicode) code.  If
               set  to the following format, it enables display and editing of original multi-byte code for-mat: format:

                   > set dspmbyte = 0000....(256 bytes)....0000

               The table requires just 256 bytes.  Each character of 256 characters corresponds  (from  left
               to right) to the ASCII codes 0x00, 0x01, ... 0xff.  Each character is set to number 0,1,2 and
               3.  Each number has the following meaning:
                 0 ... not used for multi-byte characters.
                 1 ... used for the first byte of a multi-byte character.
                 2 ... used for the second byte of a multi-byte character.
                 3 ... used for both the first byte and second byte of a multi-byte character.

               If set to `001322', the first character (means 0x00 of the ASCII code) and  second  character
               (means  0x01  of ASCII code) are set to `0'.  Then, it is not used for multi-byte characters.
               The 3rd character (0x02) is set to '1', indicating that it is used for the first  byte  of  a
               multi-byte  character.   The  4th  character(0x03) is set '3'.  It is used for both the first
               byte and the second byte of a multi-byte character.  The 5th and 6th  characters  (0x04,0x05)
               are  set to '2', indicating that they are used for the second byte of a multi-byte character.

               The GNU fileutils version of ls cannot display multi-byte filenames without the -N  (  --lit-eral --literal
               eral  ) option.   If you are using this version, set the second word of dspmbyte to "ls".  If
               not, for example, "ls-F -l" cannot display multi-byte filenames.

               This variable can only be used if KANJI and DSPMBYTE has been defined at compile time.

       dunique (+)
               If set, pushd removes any instances of name from the stack before pushing it onto the  stack.

       echo    If  set,  each  command  with  its  arguments is echoed just before it is executed.  For non-builtin nonbuiltin
               builtin commands all expansions occur before echoing.  Builtin  commands  are  echoed  before
               command  and  filename  substitution,  because these substitutions are then done selectively.
               Set by the -x command line option.

       echo_style (+)
               The style of the echo builtin.  May be set to

               bsd     Don't echo a newline if the first argument is `-n'.
               sysv    Recognize backslashed escape sequences in echo strings.
               both    Recognize both the `-n' flag and backslashed escape sequences; the default.
               none    Recognize neither.

               Set by default to the local system default.  The BSD and System V options  are  described  in
               the echo(1) man pages on the appropriate systems.

       edit (+)
               If set, the command-line editor is used.  Set by default in interactive shells.

       ellipsis (+)
               If  set,  the  `%c'/`%.'  and  `%C' prompt sequences (see the prompt shell variable) indicate
               skipped directories with an ellipsis (`...')  instead of `/<skipped>'.

       fignore (+)
               Lists file name suffixes to be ignored by completion.

       filec   In tcsh, completion is always used and this variable is ignored by default. If edit is unset,
               then the traditional csh completion is used.  If set in csh, filename completion is used.

       gid (+) The user's real group ID.

       group (+)
               The user's group name.

               If  set,  the  incremental  search  match  (in i-search-back and i-search-fwd) and the region
               between the mark and the cursor are highlighted in reverse video.

               Highlighting requires more frequent terminal writes, which introduces extra overhead. If  you
               care about terminal performance, you may want to leave this unset.

               A  string  value  determining  the characters used in History substitution (q.v.).  The first
               character of its value is used as the history substitution character, replacing  the  default
               character `!'.  The second character of its value replaces the character `^' in quick substi-tutions. substitutions.

       histdup (+)
               Controls handling of duplicate entries in the history list.  If set to `all' only unique his-tory history
               tory  events are entered in the history list.  If set to `prev' and the last history event is
               the same as the current command, then the current command is not entered in the history.   If
               set  to  `erase'  and the same event is found in the history list, that old event gets erased
               and the current one gets inserted.  Note that the `prev' and `all' options  renumber  history
               events so there are no gaps.

       histfile (+)
               The  default  location  in  which  `history -S' and `history -L' look for a history file.  If
               unset, ~/.history is used.  histfile is useful when sharing the same home  directory  between
               different  machines,  or when saving separate histories on different terminals.  Because only
               ~/.tcshrc is normally sourced before ~/.history, histfile should be set in  ~/.tcshrc  rather
               than ~/.login.

       histlit (+)
               If  set,  builtin and editor commands and the savehist mechanism use the literal (unexpanded)
               form of lines in the history list.  See also the toggle-literal-history editor command.

       history The first word indicates the number of history events to save.  The optional second word  (+)
               indicates  the format in which history is printed; if not given, `%h\t%T\t%R\n' is used.  The
               format sequences are described below under prompt; note the variable meaning of `%R'.  Set to
               `100' by default.

       home    Initialized  to  the  home directory of the invoker.  The filename expansion of `~' refers to
               this variable.

               If set to the empty string or `0' and the input device is a terminal, the end-of-file command
               (usually  generated  by  the  user by typing `^D' on an empty line) causes the shell to print
               `Use "exit" to leave tcsh.' instead of exiting.  This prevents the  shell  from  accidentally
               being  killed.   Historically this setting exited after 26 successive EOF's to avoid infinite
               loops.  If set to a number n, the shell ignores n - 1 consecutive end-of-files and  exits  on
               the nth.  (+) If unset, `1' is used, i.e., the shell exits on a single `^D'.

       implicitcd (+)
               If  set,  the shell treats a directory name typed as a command as though it were a request to
               change to that directory.  If set to verbose, the change of directory is echoed to the  stan-dard standard
               dard  output.   This  behavior  is inhibited in non-interactive shell scripts, or for command
               strings with more than one word.  Changing directory takes precedence over executing a  like-named likenamed
               named  command, but it is done after alias substitutions.  Tilde and variable expansions work
               as expected.

       inputmode (+)
               If set to `insert' or `overwrite', puts the editor into that input mode at the  beginning  of
               each line.

       killdup (+)
               Controls handling of duplicate entries in the kill ring.  If set to `all' only unique strings
               are entered in the kill ring.  If set to `prev' and the last killed string is the same as the
               current killed string, then the current string is not entered in the ring.  If set to `erase'
               and the same string is found in the kill ring, the old string is erased and the  current  one
               is inserted.

       killring (+)
               Indicates  the number of killed strings to keep in memory.  Set to `30' by default.  If unset
               or set to less than `2', the shell will only keep the most recently killed  string.   Strings
               are put in the killring by the editor commands that delete (kill) strings of text, e.g. back-ward-delete-word, backward-delete-word,
               ward-delete-word, kill-line, etc, as well as the copy-region-as-kill command.  The yank  edi-tor editor
               tor  command  will yank the most recently killed string into the command-line, while yank-pop
               (see Editor commands) can be used to yank earlier killed strings.

       listflags (+)
               If set to `x', `a' or `A', or any combination thereof (e.g., `xA'), they are used as flags to
               ls-F, making it act like `ls -xF', `ls -Fa', `ls -FA' or a combination (e.g., `ls -FxA'): `a'
               shows all files (even if they start with a `.'), `A' shows all files but `.'  and  `..',  and
               `x'  sorts across instead of down.  If the second word of listflags is set, it is used as the
               path to `ls(1)'.

       listjobs (+)
               If set, all jobs are listed when a job is suspended.  If set to `long',  the  listing  is  in
               long format.

       listlinks (+)
               If set, the ls-F builtin command shows the type of file to which each symbolic link points.

       listmax (+)
               The  maximum  number  of items which the list-choices editor command will list without asking

       listmaxrows (+)
               The maximum number of rows of items which the list-choices editor command will  list  without
               asking first.

       loginsh (+)
               Set  by  the  shell  if  it  is a login shell.  Setting or unsetting it within a shell has no
               effect.  See also shlvl.

       logout (+)
               Set by the shell to `normal' before a normal logout, `automatic' before an automatic  logout,
               and  `hangup' if the shell was killed by a hangup signal (see Signal handling).  See also the
               autologout shell variable.

       mail    The names of the files or directories to check for incoming mail,  separated  by  whitespace,
               and  optionally  preceded  by  a numeric word.  Before each prompt, if 10 minutes have passed
               since the last check, the shell checks each file and says `You have new mail.' (or,  if  mail
               contains  multiple  files, `You have new mail in name.') if the filesize is greater than zero
               in size and has a modification time greater than its access time.

               If you are in a login shell, then no mail file is reported unless it has been modified  after
               the  time  the shell has started up, to prevent redundant notifications.  Most login programs
               will tell you whether or not you have mail when you log in.

               If a file specified in mail is a directory, the shell will count each file within that direc-tory directory
               tory  as  a  separate  message,  and  will report `You have n mails.' or `You have n mails in
               name.' as appropriate.  This functionality is provided  primarily  for  those  systems  which
               store mail in this manner, such as the Andrew Mail System.

               If  the  first  word of mail is numeric it is taken as a different mail checking interval, in

               Under very rare circumstances, the shell may report `You have mail.' instead of `You have new

       matchbeep (+)
               If  set to `never', completion never beeps.  If set to `nomatch', it beeps only when there is
               no match.  If set to `ambiguous', it beeps when there are multiple matches.  If set to `notu-nique', `notunique',
               nique',  it beeps when there is one exact and other longer matches.  If unset, `ambiguous' is

       nobeep (+)
               If set, beeping is completely disabled.  See also visiblebell.

               If set, restrictions are placed on output redirection to insure that files are  not  acciden-tally accidentally
               tally  destroyed  and  that  `>>'  redirections  refer to existing files, as described in the
               Input/output section.

       noding  If set, disable the printing of `DING!' in the prompt time specifiers at the change of  hour.

       noglob  If set, Filename substitution and Directory stack substitution (q.v.) are inhibited.  This is
               most useful in shell scripts which do not deal with filenames, or after a list  of  filenames
               has been obtained and further expansions are not desirable.

       nokanji (+)
               If  set and the shell supports Kanji (see the version shell variable), it is disabled so that
               the meta key can be used.

               If set, a Filename substitution or Directory stack substitution (q.v.) which does  not  match
               any  existing files is left untouched rather than causing an error.  It is still an error for
               the substitution to be malformed, e.g., `echo [' still gives an error.

       nostat (+)
               A list of directories (or glob-patterns which match directories; see  Filename  substitution)
               that  should not be stat(2)ed during a completion operation.  This is usually used to exclude
               directories which take too much time to stat(2), for example /afs.

       notify  If set, the shell announces job completions asynchronously.  The default is  to  present  job
               completions just before printing a prompt.

       oid (+) The user's real organization ID.  (Domain/OS only)

       owd (+) The  old working directory, equivalent to the `-' used by cd and pushd.  See also the cwd and
               dirstack shell variables.

       padhour If set, enable the printing of padding '0' for hours, in  24  and  12  hour  formats.   E.G.:
               07:45:42 vs. 7:45:42

       path    A  list  of  directories in which to look for executable commands.  A null word specifies the
               current directory.  If there is no path variable then only  full  path  names  will  execute.
               path  is  set by the shell at startup from the PATH environment variable or, if PATH does not
               exist, to a system-dependent default something like `(/usr/local/bin /usr/bsd  /bin  /usr/bin
               .)'.  The shell may put `.' first or last in path or omit it entirely depending on how it was
               compiled; see the version shell variable.  A shell which is given neither the -c nor  the  -t
               option  hashes  the contents of the directories in path after reading ~/.tcshrc and each time
               path is reset.  If one adds a new command to a directory in path while the shell  is  active,
               one may need to do a rehash for the shell to find it.

       printexitvalue (+)
               If  set  and an interactive program exits with a non-zero status, the shell prints `Exit sta-tus'. status'.

       prompt  The string which is printed before reading  each  command  from  the  terminal.   prompt  may
               include any of the following formatting sequences (+), which are replaced by the given infor-mation: information:

               %/  The current working directory.
               %~  The current working directory, but with one's home directory represented by `~' and other
                   users'  home  directories  represented  by `~user' as per Filename substitution.  `~user'
                   substitution happens only if the shell has already used `~user' in a pathname in the cur-rent current
                   rent session.
               %c[[0]n], %.[[0]n]
                   The  trailing  component  of the current working directory, or n trailing components if a
                   digit n is given.  If n begins with `0', the number of  skipped  components  precede  the
                   trailing component(s) in the format `/<skipped>trailing'.  If the ellipsis shell variable
                   is set, skipped components are represented by an ellipsis so the whole becomes `...trail-ing'. `...trailing'.
                   ing'.   `~'  substitution is done as in `%~' above, but the `~' component is ignored when
                   counting trailing components.
               %C  Like %c, but without `~' substitution.
               %h, %!, !
                   The current history event number.
               %M  The full hostname.
               %m  The hostname up to the first `.'.
               %S (%s)
                   Start (stop) standout mode.
               %B (%b)
                   Start (stop) boldfacing mode.
               %U (%u)
                   Start (stop) underline mode.
               %t, %@
                   The time of day in 12-hour AM/PM format.
               %T  Like `%t', but in 24-hour format (but see the ampm shell variable).
               %p  The `precise' time of day in 12-hour AM/PM format, with seconds.
               %P  Like `%p', but in 24-hour format (but see the ampm shell variable).
               \c  c is parsed as in bindkey.
               ^c  c is parsed as in bindkey.
               %%  A single `%'.
               %n  The user name.
               %j  The number of jobs.
               %d  The weekday in `Day' format.
               %D  The day in `dd' format.
               %w  The month in `Mon' format.
               %W  The month in `mm' format.
               %y  The year in `yy' format.
               %Y  The year in `yyyy' format.
               %l  The shell's tty.
               %L  Clears from the end of the prompt to end of the display or the end of the line.
               %$  Expands the shell or environment variable name immediately after the `$'.
               %#  `>' (or the first character of the promptchars shell variable) for normal users, `#'  (or
                   the second character of promptchars) for the superuser.
                   Includes  string as a literal escape sequence.  It should be used only to change terminal
                   attributes and should not move the cursor location.  This cannot be the last sequence  in
               %?  The return code of the command executed just before the prompt.
               %R  In prompt2, the status of the parser.  In prompt3, the corrected string.  In history, the
                   history string.

               `%B', `%S', `%U' and `%{string%}' are available in only eight-bit-clean shells; see the  ver-sion version
               sion shell variable.

               The  bold,  standout and underline sequences are often used to distinguish a superuser shell.
               For example,

                   > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
                   tut [37] [2:54pm] [/usr/accts/sys] you rang? _

               If `%t', `%@', `%T', `%p', or `%P' is used, and noding is not set, then print `DING!' on  the
               change of hour (i.e, `:00' minutes) instead of the actual time.

               Set by default to `%# ' in interactive shells.

       prompt2 (+)
               The  string  with  which  to prompt in while and foreach loops and after lines ending in `\'.
               The same format sequences may be used as in prompt (q.v.); note the variable meaning of `%R'.
               Set by default to `%R? ' in interactive shells.

       prompt3 (+)
               The string with which to prompt when confirming automatic spelling correction.  The same for-mat format
               mat sequences may be used as in prompt (q.v.); note the variable meaning  of  `%R'.   Set  by
               default to `CORRECT>%R (y|n|e|a)? ' in interactive shells.

       promptchars (+)
               If set (to a two-character string), the `%#' formatting sequence in the prompt shell variable
               is replaced with the first character for normal users and the second character for the  supe-ruser. superuser.

       pushdtohome (+)
               If set, pushd without arguments does `pushd ~', like cd.

       pushdsilent (+)
               If set, pushd and popd do not print the directory stack.

       recexact (+)
               If set, completion completes on an exact match even if a longer match is possible.

       recognize_only_executables (+)
               If set, command listing displays only files in the path that are executable.  Slow.

       rmstar (+)
               If set, the user is prompted before `rm *' is executed.

       rprompt (+)
               The  string  to print on the right-hand side of the screen (after the command input) when the
               prompt is being displayed on the left.  It  recognizes  the  same  formatting  characters  as
               prompt.   It  will  automatically disappear and reappear as necessary, to ensure that command
               input isn't obscured, and will appear only if the prompt, command input, and itself will  fit
               together on the first line.  If edit isn't set, then rprompt will be printed after the prompt
               and before the command input.

       savedirs (+)
               If set, the shell does `dirs -S' before exiting.  If the first word is set to  a  number,  at
               most that many directory stack entries are saved.

               If set, the shell does `history -S' before exiting.  If the first word is set to a number, at
               most that many lines are saved.  (The number must be less than or equal to history.)  If  the
               second  word  is  set  to  `merge', the history list is merged with the existing history file
               instead of replacing it (if there is one) and sorted by time stamp and the most recent events
               are retained.  (+)

       sched (+)
               The  format  in  which  the  sched  builtin  command  prints  scheduled events; if not given,
               `%h\t%T\t%R\n' is used.  The format sequences are described  above  under  prompt;  note  the
               variable meaning of `%R'.

       shell   The file in which the shell resides.  This is used in forking shells to interpret files which
               have execute bits set, but which are not executable by the system.  (See the  description  of
               Builtin  and  non-builtin  command execution.)  Initialized to the (system-dependent) home of
               the shell.

       shlvl (+)
               The number of nested shells.  Reset to 1 in login shells.  See also loginsh.

       status  The status returned by the last command.  If it terminated abnormally, then 0200 is added  to
               the  status.   Builtin commands which fail return exit status `1', all other builtin commands
               return status `0'.

       symlinks (+)
               Can be set to several different values to control symbolic link (`symlink') resolution:

               If set to `chase', whenever the current directory changes to a directory  containing  a  sym-bolic symbolic
               bolic  link, it is expanded to the real name of the directory to which the link points.  This
               does not work for the user's home directory; this is a bug.

               If set to `ignore', the shell tries to construct a current directory relative to the  current
               directory  before  the  link  was crossed.  This means that cding through a symbolic link and
               then `cd ..'ing returns one to the original directory.  This affects  only  builtin  commands
               and filename completion.

               If  set  to  `expand',  the shell tries to fix symbolic links by actually expanding arguments
               which look like path names.  This affects any command,  not  just  builtins.   Unfortunately,
               this  does  not  work  for  hard-to-recognize  filenames,  such  as those embedded in command
               options.  Expansion may be prevented by quoting.  While this setting is usually the most con-venient, convenient,
               venient,  it  is  sometimes  misleading and sometimes confusing when it fails to recognize an
               argument which should be expanded.  A compromise is to use `ignore' and use the  editor  com-mand command
               mand normalize-path (bound by default to ^X-n) when necessary.

               Some examples are in order.  First, let's set up some play directories:

                   > cd /tmp
                   > mkdir from from/src to
                   > ln -s from/src to/dst

               Here's the behavior with symlinks unset,

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               here's the behavior with symlinks set to `chase',

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               here's the behavior with symlinks set to `ignore',

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               and here's the behavior with symlinks set to `expand'.

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd
                   > cd /tmp/to/dst; echo $cwd
                   > cd ".."; echo $cwd
                   > /bin/echo ..
                   > /bin/echo ".."

               Note  that  `expand'  expansion  1) works just like `ignore' for builtins like cd, 2) is pre-vented prevented
               vented by quoting, and 3) happens before filenames are passed to non-builtin commands.

       tcsh (+)
               The version number of the shell in the format `R.VV.PP', where `R' is the major release  num-ber, number,
               ber, `VV' the current version and `PP' the patchlevel.

       term    The terminal type.  Usually set in ~/.login as described under Startup and shutdown.

       time    If  set  to  a number, then the time builtin (q.v.) executes automatically after each command
               which takes more than that many CPU seconds.  If there is a second word, it is used as a for-mat format
               mat  string  for  the output of the time builtin.  (u) The following sequences may be used in
               the format string:

               %U  The time the process spent in user mode in cpu seconds.
               %S  The time the process spent in kernel mode in cpu seconds.
               %E  The elapsed (wall clock) time in seconds.
               %P  The CPU percentage computed as (%U + %S) / %E.
               %W  Number of times the process was swapped.
               %X  The average amount in (shared) text space used in Kbytes.
               %D  The average amount in (unshared) data/stack space used in Kbytes.
               %K  The total space used (%X + %D) in Kbytes.
               %M  The maximum memory the process had in use at any time in Kbytes.
               %F  The number of major page faults (page needed to be brought from disk).
               %R  The number of minor page faults.
               %I  The number of input operations.
               %O  The number of output operations.
               %r  The number of socket messages received.
               %s  The number of socket messages sent.
               %k  The number of signals received.
               %w  The number of voluntary context switches (waits).
               %c  The number of involuntary context switches.

               Only the first four sequences are supported on systems without BSD resource limit  functions.
               The  default  time format is `%Uu %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww' for systems that support
               resource usage reporting and `%Uu %Ss %E %P' for systems that do not.

               Under Sequent's DYNIX/ptx, %X, %D, %K, %r and %s are not available, but the  following  addi-tional additional
               tional sequences are:

               %Y  The number of system calls performed.
               %Z  The number of pages which are zero-filled on demand.
               %i  The number of times a process's resident set size was increased by the kernel.
               %d  The number of times a process's resident set size was decreased by the kernel.
               %l  The number of read system calls performed.
               %m  The number of write system calls performed.
               %p  The number of reads from raw disk devices.
               %q  The number of writes to raw disk devices.

               and  the default time format is `%Uu %Ss %E %P %I+%Oio %Fpf+%Ww'.  Note that the CPU percent-age percentage
               age can be higher than 100% on multi-processors.

       tperiod (+)
               The period, in minutes, between executions of the periodic special alias.

       tty (+) The name of the tty, or empty if not attached to one.

       uid (+) The user's real user ID.

       user    The user's login name.

       verbose If set, causes the words of each command to be printed, after history substitution (if  any).
               Set by the -v command line option.

       version (+)
               The  version  ID  stamp.   It contains the shell's version number (see tcsh), origin, release
               date, vendor, operating system and machine (see VENDOR, OSTYPE and MACHTYPE) and a comma-sep-arated comma-separated
               arated  list  of options which were set at compile time.  Options which are set by default in
               the distribution are noted.

               8b    The shell is eight bit clean; default
               7b    The shell is not eight bit clean
               wide  The shell is multibyte encoding clean (like UTF-8)
               nls   The system's NLS is used; default for systems with NLS
               lf    Login shells execute /etc/csh.login before instead of after /etc/csh.cshrc and ~/.login
                     before instead of after ~/.tcshrc and ~/.history.
               dl    `.' is put last in path for security; default
               nd    `.' is omitted from path for security
               vi    vi-style editing is the default rather than emacs
               dtr   Login shells drop DTR when exiting
               bye   bye is a synonym for logout and log is an alternate name for watchlog
               al    autologout is enabled; default
               kan   Kanji  is  used  if  appropriate according to locale settings, unless the nokanji shell
                     variable is set
               sm    The system's malloc(3) is used
               hb    The `#!<program> <args>' convention is emulated when executing shell scripts
               ng    The newgrp builtin is available
               rh    The shell attempts to set the REMOTEHOST environment variable
               afs   The shell verifies your password with  the  kerberos  server  if  local  authentication
                     fails.   The  afsuser  shell variable or the AFSUSER environment variable override your
                     local username if set.

               An administrator may enter additional strings to indicate differences in the local version.

       visiblebell (+)
               If set, a screen flash is used rather than the audible bell.  See also nobeep.

       watch (+)
               A list of user/terminal pairs to watch for logins and logouts.  If either the user  is  `any'
               all  terminals  are  watched for the given user and vice versa.  Setting watch to `(any any)'
               watches all users and terminals.  For example,

                   set watch = (george ttyd1 any console $user any)

               reports activity of the user `george' on ttyd1, any user on the console, and  oneself  (or  a
               trespasser) on any terminal.

               Logins  and  logouts are checked every 10 minutes by default, but the first word of watch can
               be set to a number to check every so many minutes.  For example,

                   set watch = (1 any any)

               reports any login/logout once every minute.  For the impatient, the log builtin command trig-gers triggers
               gers  a  watch report at any time.  All current logins are reported (as with the log builtin)
               when watch is first set.

               The who shell variable controls the format of watch reports.

       who (+) The format string for watch messages.  The following sequences  are  replaced  by  the  given

               %n  The name of the user who logged in/out.
               %a  The observed action, i.e., `logged on', `logged off' or `replaced olduser on'.
               %l  The terminal (tty) on which the user logged in/out.
               %M  The  full  hostname of the remote host, or `local' if the login/logout was from the local
               %m  The hostname of the remote host up to the first `.'.  The full name is printed if  it  is
                   an IP address or an X Window System display.

               %M  and  %m  are  available  on only systems that store the remote hostname in /etc/utmp.  If
               unset, `%n has %a %l from %m.' is used, or `%n has %a %l.' on systems which don't  store  the
               remote hostname.

       wordchars (+)
               A  list  of  non-alphanumeric characters to be considered part of a word by the forward-word,
               backward-word etc., editor commands.  If unset, `*?_-.[]~=' is used.

       AFSUSER (+)
               Equivalent to the afsuser shell variable.

       COLUMNS The number of columns in the terminal.  See Terminal management.

       DISPLAY Used by X Window System (see X(1)).  If set, the shell does not set autologout (q.v.).

       EDITOR  The pathname to a default editor.  See also the VISUAL environment variable and  the  run-fg-editor run-fgeditor
               editor editor command.

       GROUP (+)
               Equivalent to the group shell variable.

       HOME    Equivalent to the home shell variable.

       HOST (+)
               Initialized  to  the  name of the machine on which the shell is running, as determined by the
               gethostname(2) system call.

       HOSTTYPE (+)
               Initialized to the type of machine on which the shell is running, as  determined  at  compile
               time.  This variable is obsolete and will be removed in a future version.

       HPATH (+)
               A  colon-separated list of directories in which the run-help editor command looks for command

       LANG    Gives the preferred character environment.  See Native Language System support.

               If set, only ctype character handling is changed.  See Native Language System support.

       LINES   The number of lines in the terminal.  See Terminal management.

               The format of this variable is reminiscent of the termcap(5) file format;  a  colon-separated
               list  of  expressions  of  the form "xx=string", where "xx" is a two-character variable name.
               The variables with their associated defaults are:

                   no   0      Normal (non-filename) text
                   fi   0      Regular file
                   di   01;34  Directory
                   ln   01;36  Symbolic link
                   pi   33     Named pipe (FIFO)
                   so   01;35  Socket
                   do   01;35  Door
                   bd   01;33  Block device
                   cd   01;32  Character device
                   ex   01;32  Executable file
                   mi   (none) Missing file (defaults to fi)
                   or   (none) Orphaned symbolic link (defaults to ln)
                   lc   ^[[    Left code
                   rc   m      Right code
                   ec   (none) End code (replaces lc+no+rc)

               You need to include only the variables you want to change from the default.

               File names can also be colorized based on filename  extension.   This  is  specified  in  the
               LS_COLORS  variable  using  the  syntax "*ext=string".  For example, using ISO 6429 codes, to
               color all C-language source files blue you would specify  "*.c=34".   This  would  color  all
               files ending in .c in blue (34) color.

               Control characters can be written either in C-style-escaped notation, or in stty-like ^-nota-tion. ^-notation.
               tion.  The C-style notation adds ^[ for Escape, _ for a normal space  character,  and  ?  for
               Delete.  In addition, the ^[ escape character can be used to override the default interpreta-tion interpretation
               tion of ^[, ^, : and =.

               Each file will be written as <lc> <color-code> <rc> <filename> <ec>.  If  the  <ec>  code  is
               undefined,  the  sequence <lc> <no> <rc> will be used instead.  This is generally more conve-nient convenient
               nient to use, but less general.  The left, right and end codes are provided so you don't have
               to  type  common parts over and over again and to support weird terminals; you will generally
               not need to change them at all unless your terminal does not use ISO 6429 color sequences but
               a different system.

               If  your  terminal  does  use ISO 6429 color codes, you can compose the type codes (i.e., all
               except the lc, rc, and ec codes) from numerical commands separated by semicolons.   The  most
               common commands are:

                       0   to restore default color
                       1   for brighter colors
                       4   for underlined text
                       5   for flashing text
                       30  for black foreground
                       31  for red foreground
                       32  for green foreground
                       33  for yellow (or brown) foreground
                       34  for blue foreground
                       35  for purple foreground
                       36  for cyan foreground
                       37  for white (or gray) foreground
                       40  for black background
                       41  for red background
                       42  for green background
                       43  for yellow (or brown) background
                       44  for blue background
                       45  for purple background
                       46  for cyan background
                       47  for white (or gray) background

               Not all commands will work on all systems or display devices.

               A  few  terminal  programs  do not recognize the default end code properly.  If all text gets
               colorized after you do a directory listing, try changing the no and fi codes from  0  to  the
               numerical codes for your standard fore- and background colors.

       MACHTYPE (+)
               The machine type (microprocessor class or machine model), as determined at compile time.

       NOREBIND (+)
               If  set,  printable  characters  are not rebound to self-insert-command.  See Native Language
               System support.

       OSTYPE (+)
               The operating system, as determined at compile time.

       PATH    A colon-separated list of directories in which to look for executables.   Equivalent  to  the
               path shell variable, but in a different format.

       PWD (+) Equivalent  to  the  cwd  shell  variable,  but not synchronized to it; updated only after an
               actual directory change.

       REMOTEHOST (+)
               The host from which the user has logged in remotely, if this is the case  and  the  shell  is
               able to determine it.  Set only if the shell was so compiled; see the version shell variable.

       SHLVL (+)
               Equivalent to the shlvl shell variable.

       SYSTYPE (+)
               The current system type.  (Domain/OS only)

       TERM    Equivalent to the term shell variable.

       TERMCAP The terminal capability string.  See Terminal management.

       USER    Equivalent to the user shell variable.

       VENDOR (+)
               The vendor, as determined at compile time.

       VISUAL  The pathname to a default full-screen editor.  See also the EDITOR environment  variable  and
               the run-fg-editor editor command.

       /etc/csh.cshrc  Read  first by every shell.  ConvexOS, Stellix and Intel use /etc/cshrc and NeXTs use
                       /etc/cshrc.std.  A/UX, AMIX, Cray and IRIX have no equivalent  in  csh(1),  but  read
                       this  file  in  tcsh  anyway.   Solaris  2.x  does not have it either, but tcsh reads
                       /etc/.cshrc.  (+)
       /etc/csh.login  Read  by  login  shells  after  /etc/csh.cshrc.   ConvexOS,  Stellix  and  Intel  use
                       /etc/login,  NeXTs  use  /etc/login.std, Solaris 2.x uses /etc/.login and A/UX, AMIX,
                       Cray and IRIX use /etc/cshrc.
       ~/.tcshrc (+)   Read by every shell after /etc/csh.cshrc or its equivalent.
       ~/.cshrc        Read by every shell, if ~/.tcshrc doesn't exist, after /etc/csh.cshrc or its  equiva-lent. equivalent.
                       lent.  This manual uses `~/.tcshrc' to mean `~/.tcshrc or, if ~/.tcshrc is not found,
       ~/.history      Read by login shells after ~/.tcshrc if savehist is set, but see also histfile.
       ~/.login        Read by login shells after ~/.tcshrc or ~/.history.  The shell  may  be  compiled  to
                       read ~/.login before instead of after ~/.tcshrc and ~/.history; see the version shell
       ~/.cshdirs (+)  Read by login shells after ~/.login if savedirs is set, but see also dirsfile.
       /etc/csh.logout Read by login shells at logout.  ConvexOS, Stellix  and  Intel  use  /etc/logout  and
                       NeXTs  use  /etc/logout.std.  A/UX, AMIX, Cray and IRIX have no equivalent in csh(1),
                       but read this file in tcsh anyway.  Solaris 2.x does not have  it  either,  but  tcsh
                       reads /etc/.logout.  (+)
       ~/.logout       Read by login shells at logout after /etc/csh.logout or its equivalent.
       /bin/sh         Used to interpret shell scripts not starting with a `#'.
       /tmp/sh*        Temporary file for `<<'.
       /etc/passwd     Source of home directories for `~name' substitutions.

       The  order  in  which startup files are read may differ if the shell was so compiled; see Startup and
       shutdown and the version shell variable.

       This manual describes tcsh as a single entity, but experienced csh(1) users will want to pay  special
       attention to tcsh's new features.

       A  command-line  editor,  which supports GNU Emacs or vi(1)-style key bindings.  See The command-line
       editor and Editor commands.

       Programmable, interactive word completion and listing.  See Completion and listing and  the  complete
       and uncomplete builtin commands.

       Spelling correction (q.v.) of filenames, commands and variables.

       Editor  commands (q.v.) which perform other useful functions in the middle of typed commands, includ-
       ing documentation lookup (run-help), quick editor restarting (run-fg-editor) and  command  resolution

       An  enhanced  history  mechanism.  Events in the history list are time-stamped.  See also the history
       command and its associated shell variables, the previously undocumented `#' event specifier  and  new
       modifiers  under  History  substitution, the *-history, history-search-*, i-search-*, vi-search-* and
       toggle-literal-history editor commands and the histlit shell variable.

       Enhanced directory parsing and directory stack handling.  See the cd, pushd, popd and  dirs  commands
       and  their associated shell variables, the description of Directory stack substitution, the dirstack,
       owd and symlinks shell variables and the normalize-command and normalize-path editor commands.

       Negation in glob-patterns.  See Filename substitution.

       New File inquiry operators (q.v.) and a filetest builtin which uses them.

       A variety of Automatic, periodic and timed events (q.v.) including scheduled events, special aliases,
       automatic logout and terminal locking, command timing and watching for logins and logouts.

       Support for the Native Language System (see Native Language System support), OS variant features (see
       OS variant support and the echo_style  shell  variable)  and  system-dependent  file  locations  (see

       Extensive terminal-management capabilities.  See Terminal management.

       New builtin commands including builtins, hup, ls-F, newgrp, printenv, which and where (q.v.).

       New variables that make useful information easily available to the shell.  See the gid, loginsh, oid,
       shlvl, tcsh, tty, uid and version shell variables  and  the  HOST,  REMOTEHOST,  VENDOR,  OSTYPE  and
       MACHTYPE environment variables.

       A new syntax for including useful information in the prompt string (see prompt).  and special prompts
       for loops and spelling correction (see prompt2 and prompt3).

       Read-only variables.  See Variable substitution.

       When a suspended command is restarted, the shell prints the directory it started in if this  is  dif-ferent different
       ferent  from the current directory.  This can be misleading (i.e., wrong) as the job may have changed
       directories internally.

       Shell builtin functions are not stoppable/restartable.  Command sequences of the form `a ; b ; c' are
       also  not  handled  gracefully  when  stopping is attempted.  If you suspend `b', the shell will then
       immediately execute `c'.  This is especially noticeable if this expansion results from an alias.   It
       suffices  to place the sequence of commands in ()'s to force it to a subshell, i.e., `( a ; b ; c )'.

       Control over tty output after processes are started is primitive; perhaps this will  inspire  someone
       to  work on a good virtual terminal interface.  In a virtual terminal interface much more interesting
       things could be done with output control.

       Alias substitution is most often used to clumsily simulate shell procedures; shell procedures  should
       be provided rather than aliases.

       Commands within loops are not placed in the history list.  Control structures should be parsed rather
       than being recognized as built-in commands.  This would allow control commands to be placed anywhere,
       to be combined with `|', and to be used with `&' and `;' metasyntax.

       foreach doesn't ignore here documents when looking for its end.

       It should be possible to use the `:' modifiers on the output of command substitutions.

       The screen update for lines longer than the screen width is very poor if the terminal cannot move the
       cursor up (i.e., terminal type `dumb').

       HPATH and NOREBIND don't need to be environment variables.

       Glob-patterns which do not use `?', `*' or `[]' or which use `{}' or `~' are not negated correctly.

       The single-command form of if does output redirection even if the expression is false and the command
       is not executed.

       ls-F includes file identification characters when sorting filenames and does not handle control char-acters characters
       acters in filenames well.  It cannot be interrupted.

       Command substitution supports multiple commands and conditions, but not cycles or backward gotos.

       Report bugs at, preferably with fixes.  If you want to  help  maintain  and  test
       tcsh,  send  mail to with the text `subscribe tcsh' on a line by itself in the

       In 1964, DEC produced the PDP-6.  The PDP-10 was a later re-implementation.  It was re-christened the
       DECsystem-10 in 1970 or so when DEC brought out the second model, the KI10.

       TENEX  was  created  at  Bolt, Beranek & Newman (a Cambridge, Massachusetts think tank) in 1972 as an
       experiment in demand-paged virtual memory operating systems.  They built a  new  pager  for  the  DEC
       PDP-10 and created the OS to go with it.  It was extremely successful in academia.

       In 1975, DEC brought out a new model of the PDP-10, the KL10; they intended to have only a version of
       TENEX, which they had licensed from BBN, for the new box.  They called their version  TOPS-20  (their
       capitalization is trademarked).  A lot of TOPS-10 users (`The OPerating System for PDP-10') objected;
       thus DEC found themselves supporting two incompatible systems on the same  hardware--but  then  there
       were 6 on the PDP-11!

       TENEX,  and  TOPS-20  to  version  3, had command completion via a user-code-level subroutine library
       called ULTCMD.  With version 3, DEC moved all that capability and more into the monitor (`kernel' for
       you Unix types), accessed by the COMND% JSYS (`Jump to SYStem' instruction, the supervisor call mech-anism mechanism
       anism [are my IBM roots also showing?]).

       The creator of tcsh was impressed by this feature and several others of TENEX and TOPS-20,  and  cre-ated created
       ated a version of csh which mimicked them.

       The system limits argument lists to ARG_MAX characters.

       The number of arguments to a command which involves filename expansion is limited to 1/6th the number
       of characters allowed in an argument list.

       Command substitutions may substitute no more characters than are allowed in an argument list.

       To detect looping, the shell restricts the number of alias substitutions on a single line to 20.

       csh(1), emacs(1),  ls(1),  newgrp(1),  sh(1),  setpath(1),  stty(1),  su(1),  tset(1),  vi(1),  x(1),
       access(2),  execve(2),  fork(2),  killpg(2),  pipe(2),  setrlimit(2),  sigvec(2),  stat(2), umask(2),
       vfork(2), wait(2), malloc(3), setlocale(3),  tty(4),  a.out(5),  termcap(5),  environ(7),  termio(7),
       Introduction to the C Shell

       This manual documents tcsh 6.17.00 (Astron) 2009-07-10.

       William Joy
         Original author of csh(1)
       J.E. Kulp, IIASA, Laxenburg, Austria
         Job control and directory stack features
       Ken Greer, HP Labs, 1981
         File name completion
       Mike Ellis, Fairchild, 1983
         Command name recognition/completion
       Paul Placeway, Ohio State CIS Dept., 1983-1993
         Command line editor, prompt routines, new glob syntax and numerous fixes and speedups
       Karl Kleinpaste, CCI 1983-4
         Special  aliases,  directory  stack extraction stuff, login/logout watch, scheduled events, and the
         idea of the new prompt format
       Rayan Zachariassen, University of Toronto, 1984
         ls-F and which builtins and numerous bug fixes, modifications and speedups
       Chris Kingsley, Caltech
         Fast storage allocator routines
       Chris Grevstad, TRW, 1987
         Incorporated 4.3BSD csh into tcsh
       Christos S. Zoulas, Cornell U. EE Dept., 1987-94
         Ports to HPUX, SVR2 and SVR3, a SysV version of getwd.c, SHORT_STRINGS support and a new version of
       James J Dempsey, BBN, and Paul Placeway, OSU, 1988
         A/UX port
       Daniel Long, NNSC, 1988
       Patrick Wolfe, Kuck and Associates, Inc., 1988
         vi mode cleanup
       David C Lawrence, Rensselaer Polytechnic Institute, 1989
         autolist and ambiguous completion listing
       Alec Wolman, DEC, 1989
         Newlines in the prompt
       Matt Landau, BBN, 1989
       Ray Moody, Purdue Physics, 1989
         Magic space bar history expansion
       Mordechai ????, Intel, 1989
         printprompt() fixes and additions
       Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989
         Automatic spelling correction and prompt3
       Per Hedeland, Ellemtel, Sweden, 1990-Various 1990Various
         Various bugfixes, improvements and manual updates
       Hans J. Albertsson (Sun Sweden)
         ampm, settc and telltc
       Michael Bloom
         Interrupt handling fixes
       Michael Fine, Digital Equipment Corp
         Extended key support
       Eric Schnoebelen, Convex, 1990
         Convex support, lots of csh bug fixes, save and restore of directory stack
       Ron Flax, Apple, 1990
         A/UX 2.0 (re)port
       Dan Oscarsson, LTH Sweden, 1990
         NLS support and simulated NLS support for non NLS sites, fixes
       Johan Widen, SICS Sweden, 1990
         shlvl, Mach support, correct-line, 8-bit printing
       Matt Day, Sanyo Icon, 1990
         POSIX termio support, SysV limit fixes
       Jaap Vermeulen, Sequent, 1990-91
         Vi mode fixes, expand-line, window change fixes, Symmetry port
       Martin Boyer, Institut de recherche d'Hydro-Quebec, 1991
         autolist  beeping  options,  modified  the  history  search to search for the whole string from the
         beginning of the line to the cursor.
       Scott Krotz, Motorola, 1991
         Minix port
       David Dawes, Sydney U. Australia, Physics Dept., 1991
         SVR4 job control fixes
       Jose Sousa, Interactive Systems Corp., 1991
         Extended vi fixes and vi delete command
       Marc Horowitz, MIT, 1991
         ANSIfication fixes, new exec hashing code, imake fixes, where
       Bruce Sterling Woodcock,, 1991-1995
         ETA and Pyramid port, Makefile and lint fixes, ignoreeof=n addition, and various other  portability
         changes and bug fixes
       Jeff Fink, 1992
         complete-word-fwd and complete-word-back
       Harry C. Pulley, 1992
         Coherent port
       Andy Phillips, Mullard Space Science Lab U.K., 1992
         VMS-POSIX port
       Beto Appleton, IBM Corp., 1992
         Walking process group fixes, csh bug fixes, POSIX file tests, POSIX SIGHUP
       Scott Bolte, Cray Computer Corp., 1992
         CSOS port
       Kaveh R. Ghazi, Rutgers University, 1992
         Tek, m88k, Titan and Masscomp ports and fixes.  Added autoconf support.
       Mark Linderman, Cornell University, 1992
         OS/2 port
       Mika Liljeberg, liljeber@kruuna.Helsinki.FI, 1992
         Linux port
       Tim P. Starrin, NASA Langley Research Center Operations, 1993
         Read-only variables
       Dave Schweisguth, Yale University, 1993-4
         New man page and tcsh.man2html
       Larry Schwimmer, Stanford University, 1993
         AFS and HESIOD patches
       Luke Mewburn, RMIT University, 1994-6
         Enhanced directory printing in prompt, added ellipsis and rprompt.
       Edward Hutchins, Silicon Graphics Inc., 1996
         Added implicit cd.
       Martin Kraemer, 1997
         Ported to Siemens Nixdorf EBCDIC machine
       Amol Deshpande, Microsoft, 1997
         Ported to WIN32 (Windows/95 and Windows/NT); wrote all the missing library and message catalog code
         to interface to Windows.
       Taga Nayuta, 1998
         Color ls additions.

       Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig, Diana Smetters,  Bob  Sutter-field, Sutterfield,
       field,  Mark  Verber,  Elizabeth  Zwicky  and  all the other people at Ohio State for suggestions and

       All the people on the net, for putting up with, reporting bugs in, and suggesting  new  additions  to
       each and every version

       Richard M. Alderson III, for writing the `T in tcsh' section

Astron 6.17.00                                  10 July 2009                                         TCSH(1)

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