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STTY(1)                   BSD General Commands Manual                  STTY(1)

NAME
     stty -- set the options for a terminal device interface

SYNOPSIS
     stty [-a | -e | -g] [-f file] [operands]

DESCRIPTION
     The stty utility sets or reports on terminal characteristics for the device that is its standard input.
     If no options or operands are specified, it reports the settings of a subset of characteristics as well
     as additional ones if they differ from their default values.  Otherwise it modifies the terminal state
     according to the specified arguments.  Some combinations of arguments are mutually exclusive on some
     terminal types.

     The following options are available:

     -a      Display all the current settings for the terminal to standard output as per IEEE Std 1003.2
             (``POSIX.2'').

     -e      Display all the current settings for the terminal to standard output in the traditional BSD
             ``all'' and ``everything'' formats.

     -f      Open and use the terminal named by file rather than using standard input.  The file is opened
             using the O_NONBLOCK flag of open(), making it possible to set or display settings on a termi-nal terminal
             nal that might otherwise block on the open.

     -g      Display all the current settings for the terminal to standard output in a form that may be used
             as an argument to a subsequent invocation of stty to restore the current terminal state as per
             IEEE Std 1003.2 (``POSIX.2'').

     The following arguments are available to set the terminal characteristics:

   Control Modes:
     Control mode flags affect hardware characteristics associated with the terminal.  This corresponds to
     the c_cflag in the termios structure.

     number      Set terminal baud rate to the number given, if possible.  If the baud rate is set to zero,
                 modem control is no longer asserted.

     clocal (-clocal)
                 Assume a line without (with) modem control.

     cread (-cread)
                 Enable (disable) the receiver.

     crtscts (-crtscts)
                 Enable (disable) RTS/CTS flow control.

     cs5 cs6 cs7 cs8
                 Select character size, if possible.

     cstopb (-cstopb)
                 Use two (one) stop bits per character.

     hup (-hup)  Same as hupcl (-hupcl).

     hupcl (-hupcl)
                 Stop asserting modem control (do not stop asserting modem control) on last close.

     ispeed number
                 Set terminal input baud rate to the number given, if possible.  If the input baud rate is
                 set to zero, the input baud rate is set to the value of the output baud rate.

     ospeed number
                 Set terminal output baud rate to the number given, if possible.  If the output baud rate is
                 set to zero, modem control is no longer asserted.

     parenb (-parenb)
                 Enable (disable) parity generation and detection.

     parodd (-parodd)
                 Select odd (even) parity.

     speed number
                 This sets both ispeed and ospeed to number.

   Input Modes:
     This corresponds to the c_iflag in the termios structure.

     brkint (-brkint)
                 Signal (do not signal) INTR on break.

     icrnl (-icrnl)
                 Map (do not map) CR to NL on input.

     ignbrk (-ignbrk)
                 Ignore (do not ignore) break on input.

     igncr (-igncr)
                 Ignore (do not ignore) CR on input.

     ignpar (-ignpar)
                 Ignore (do not ignore) characters with parity errors.

     imaxbel (-imaxbel)
                 The system imposes a limit of MAX_INPUT (currently 255) characters in the input queue.  If
                 imaxbel is set and the input queue limit has been reached, subsequent input causes the sys-tem system
                 tem to send an ASCII BEL character to the output queue (the terminal beeps at you).  Other-wise, Otherwise,
                 wise, if imaxbel is unset and the input queue is full, the next input character causes the
                 entire input and output queues to be discarded.

     inlcr (-inlcr)
                 Map (do not map) NL to CR on input.

     inpck (-inpck)
                 Enable (disable) input parity checking.

     istrip (-istrip)
                 Strip (do not strip) input characters to seven bits.

     iutf8 (-iutf8)
                 Assume input characters are UTF-8 encoded.

     ixany (-ixany)
                 Allow any character (allow only START) to restart output.

     ixoff (-ixoff)
                 Request that the system send (not send) START/STOP characters when the input queue is
                 nearly empty/full.

     ixon (-ixon)
                 Enable (disable) START/STOP output control.  Output from the system is stopped when the
                 system receives STOP and started when the system receives START, or if ixany is set, any
                 character restarts output.

     parmrk (-parmrk)
                 Mark (do not mark) characters with parity errors.

   Output Modes:
     This corresponds to the c_oflag of the termios structure.

     bs0 bs1     Select the style of delay for backspaces (e.g., set BSDLY to BS0).

     cr0 cr1 cr2 cr3
                 Select the style of delay for carriage returns (e.g., set CRDLY to CR0).

     ff0 ff1     Select the style of delay for form feeds (e.g., set FFDLY to FF0).

     nl0 nl1     Select the style of delay for newlines (e.g., set NLDLY to NL0).

     ocrnl (-ocrnl)
                 Map (do not map) carriage return to newline on output.

     ofdel (-odell)
                 Use DELs (NULs) as fill characters.

     ofill (-ofill)
                 Use fill characters (use timing) for delays.

     onlcr (-onlcr)
                 Map (do not map) NL to CR-NL on output.

     onlret (-onlret)
                 On the terminal, NL performs (does not perform) the CR function.

     onocr (-onocr)
                 Do not (do) output CRs at column zero.

     opost (-opost)
                 Post-process output (do not post-process output; ignore all other output modes).

     oxtabs (-oxtabs)
                 Expand (do not expand) tabs to spaces on output.

     tab0 tab1 tab2 tab3
                 Select the style of delay for horizontal tabs (e.g., set TABDLY to TAB0).

     tabs (-tabs)
                 Same as tab0 (tab3).

     vt0 vt1     Select the style of delay for vertical tabs (e.g., set VTDLY to VT0).

   Local Modes:
     Local mode flags (lflags) affect various and sundry characteristics of terminal processing.  Histori-cally Historically
     cally the term "local" pertained to new job control features implemented by Jim Kulp on a Pdp 11/70 at
     IIASA.  Later, the driver ran on the first VAX at Evans Hall, UC Berkeley, where the job control
     details were greatly modified, but the structure definitions and names remained essentially unchanged.
     The second interpretation of the 'l' in lflag is ``line discipline flag'', which corresponds to the
     c_lflag of the termios structure.

     altwerase (-altwerase)
                 Use (do not use) an alternate word erase algorithm when processing WERASE characters.  This
                 alternate algorithm considers sequences of alphanumeric/underscores as words.  It also
                 skips the first preceding character in its classification (as a convenience, since the one
                 preceding character could have been erased with simply an ERASE character.)

     echo (-echo)
                 Echo back (do not echo back) every character typed.

     echoctl (-echoctl)
                 If echoctl is set, echo control characters as ^X.  Otherwise, control characters echo as
                 themselves.

     echoe (-echoe)
                 The ERASE character shall (shall not) visually erase the last character in the current line
                 from the display, if possible.

     echok (-echok)
                 Echo (do not echo) NL after KILL character.

     echoke (-echoke)
                 The KILL character shall (shall not) visually erase the current line from the display, if
                 possible.

     echonl (-echonl)
                 Echo (do not echo) NL, even if echo is disabled.

     echoprt (-echoprt)
                 For printing terminals.  If set, echo erased characters backwards within ``\'' and ``/''.
                 Otherwise, disable this feature.

     flusho (-flusho)
                 Indicates output is (is not) being discarded.

     icanon (-icanon)
                 Enable (disable) canonical input (ERASE and KILL processing).

     iexten (-iexten)
                 Enable (disable) any implementation-defined special control characters that are not cur-rently currently
                 rently controlled by icanon, isig, ixoff, or ixon.

     isig (-isig)
                 Enable (disable) the checking of characters against the special control characters INTR,
                 QUIT, and SUSP.

     mdmbuf (-mdmbuf)
                 If set, flow control output based on condition of Carrier Detect.  Otherwise, writes return
                 an error if Carrier Detect is low (and Carrier is not being ignored with the CLOCAL flag.)

     noflsh (-noflsh)
                 Disable (enable) flush after INTR, QUIT, or SUSP.

     pendin (-pendin)
                 Indicates input is (is not) pending after a switch from non-canonical to canonical mode and
                 will be re-input when a read becomes pending or more input arrives.

     tostop (-tostop)
                 Send (do not send) SIGTTOU for background output.  This causes background jobs to stop if
                 they attempt terminal output.

   Control Characters:
     control-character string
                 Set control-character to string.  If string is a single character, the control character is
                 set to that character.  If string is the two character sequence "^-" or the string "undef"
                 the control character is disabled (i.e. set to {_POSIX_VDISABLE}.)

                 Recognized control-characters:


                       control-character controlcharacter
                       character    Subscript    Description
                       _________    _________    _______________
                       eof          VEOF         EOF character
                       eol          VEOL         EOL character
                       eol2         VEOL2        EOL2 character
                       erase        VERASE       ERASE character
                       erase2       VERASE2      ERASE2 character
                       werase       VWERASE      WERASE character
                       intr         VINTR        INTR character
                       kill         VKILL        KILL character
                       quit         VQUIT        QUIT character
                       susp         VSUSP        SUSP character
                       start        VSTART       START character
                       stop         VSTOP        STOP character
                       dsusp        VDSUSP       DSUSP character
                       lnext        VLNEXT       LNEXT character
                       reprint      VREPRINT     REPRINT character
                       status       VSTATUS      STATUS character

     min number

     time number
                 Set the value of min or time to number.  MIN and TIME are used in Non-Canonical mode input
                 processing (-icanon).

   Combination Modes:
     saved settings
                 Set the current terminal characteristics to the saved settings produced by the -g option.

     cols number
                 Same as columns.

     columns number
                 The terminal size is recorded as having number columns.

     crt (-crt)  Set (disable) all modes suitable for a CRT display device.

     dec         Set modes suitable for users of Digital Equipment Corporation systems (ERASE, KILL, and
                 INTR characters are set to ^?, ^U, and ^C; ixany is disabled, and crt is enabled.)

     ek          Reset ERASE, ERASE2, and KILL characters back to system defaults.

     -evenp      Same as -oddp and -parity.

     evenp       Enable parenb and cs7; disable parodd.

     extproc (-extproc)
                 If set, this flag indicates that some amount of terminal processing is being performed by
                 either the terminal hardware or by the remote side connected to a pty.

     kerninfo (-kerninfo)
                 Enable (disable) the system generated status line associated with processing a STATUS char-acter character
                 acter (usually set to ^T).  The status line consists of the system load average, the cur-rent current
                 rent command name, its process ID, the event the process is waiting on (or the status of
                 the process), the user and system times, percent cpu, and current memory usage.

     nl (-nl)    Enable (disable) icrnl.  In addition, -nl unsets inlcr and igncr.

     -oddp       Same as -evenp and -parity.

     oddp        Enable parenb, cs7, and parodd.

     -parity     Disable parenb; set cs8.

     parity      Same as evenp.

     raw (-raw)  If set, change the modes of the terminal so that no input or output processing is per-formed. performed.
                 formed.  If unset, change the modes of the terminal to some reasonable state that performs
                 input and output processing.  Note that since the terminal driver no longer has a single
                 RAW bit, it is not possible to intuit what flags were set prior to setting raw.  This means
                 that unsetting raw may not put back all the setting that were previously in effect.  To set
                 the terminal into a raw state and then accurately restore it, the following shell code is
                 recommended:

                 save_state=$(stty -g)
                 stty raw
                 ...
                 stty "$save_state"

     rows number
                 The terminal size is recorded as having number rows.

     sane        Resets all modes to reasonable values for interactive terminal use.

     size        The size of the terminal is printed as two numbers on a single line, first rows, then col-umns. columns.
                 umns.

     tty         Set the line discipline to the standard terminal line discipline TTYDISC.

   Compatibility Modes:
     These modes remain for compatibility with the previous version of the stty command.

     all         Reports all the terminal modes as with stty -a, except that the control characters are
                 printed in a columnar format.

     brk value   Same as the control character eol.

     cbreak      If set, enables brkint, ixon, imaxbel, opost, isig, iexten, and -icanon.  If unset, same as
                 sane.

     cooked      Same as sane.

     crtbs (-crtbs)
                 Same as echoe.

     crterase (-crterase)
                 Same as echoe.

     crtkill (-crtkill)
                 Same as echoke.

     ctlecho (-ctlecho)
                 Same as echoctl.

     decctlq (-decctlq)
                 The converse of ixany.

     everything  Same as all.

     flush value
                 Same as the control character discard.

     litout (-litout)
                 The converse of opost.

     new         Same as tty.

     newcrt (-newcrt)
                 Same as crt.

     old         Same as tty.

     pass8       The converse of parity.

     prterase (-prterase)
                 Same as echoprt.

     rprnt value
                 Same as the control character reprint.

     tabs (-tabs)
                 The converse of oxtabs.

     tandem (-tandem)
                 Same as ixoff.

DIAGNOSTICS
     The stty utility exits 0 on success, and >0 if an error occurs.

LEGACY DESCRIPTION
     In legacy operation, the bs[01], cr[0-3], ff[01], nl[01], tab[0-3], and vt[01] control modes are not
     accepted, nor are ocrnl (-ocrnl), ofdel (-ofdel), ofill (-ofill), onlret (-onlret), and onocr (-onocr).

     For more information about legacy mode, see compat(5).

SEE ALSO
     termios(4), compat(5)

STANDARDS
     The stty utility is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible.  The flags -e and -f are
     extensions to the standard.

BSD                             April 18, 1994                             BSD

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