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PRINTF(1)                 BSD General Commands Manual                PRINTF(1)

NAME
     printf -- formatted output

SYNOPSIS
     printf format [arguments ...]

DESCRIPTION
     The printf utility formats and prints its arguments, after the first, under control of the format.  The
     format is a character string which contains three types of objects: plain characters, which are simply
     copied to standard output, character escape sequences which are converted and copied to the standard
     output, and format specifications, each of which causes printing of the next successive argument.

     The arguments after the first are treated as strings if the corresponding format is either c, b or s;
     otherwise it is evaluated as a C constant, with the following extensions:

           •   A leading plus or minus sign is allowed.
           •   If the leading character is a single or double quote, the value is the ASCII code of the next
               character.

     The format string is reused as often as necessary to satisfy the arguments.  Any extra format specifi-cations specifications
     cations are evaluated with zero or the null string.

     Character escape sequences are in backslash notation as defined in the ANSI X3.159-1989 (``ANSI C89''),
     with extensions.  The characters and their meanings are as follows:

           \a      Write a <bell> character.
           \b      Write a <backspace> character.
           \c      Ignore remaining characters in this string.
           \f      Write a <form-feed> character.
           \n      Write a <new-line> character.
           \r      Write a <carriage return> character.
           \t      Write a <tab> character.
           \v      Write a <vertical tab> character.
           \'      Write a <single quote> character.
           \\      Write a backslash character.
           \num
           \0num   Write an 8-bit character whose ASCII value is the 1-, 2-, or 3-digit octal number num.

     Each format specification is introduced by the percent character (``%'').  The remainder of the format
     specification includes, in the following order:

     Zero or more of the following flags:

             #       A `#' character specifying that the value should be printed in an ``alternate form''.
                     For c, d, and s, formats, this option has no effect.  For the o formats the precision
                     of the number is increased to force the first character of the output string to a zero.
                     For the x (X) format, a non-zero result has the string 0x (0X) prepended to it.  For e,
                     E, f, g, and G, formats, the result will always contain a decimal point, even if no
                     digits follow the point (normally, a decimal point only appears in the results of those
                     formats if a digit follows the decimal point).  For g and G formats, trailing zeros are
                     not removed from the result as they would otherwise be;

             -       A minus sign `-' which specifies left adjustment of the output in the indicated field;

             +       A `+' character specifying that there should always be a sign placed before the number
                     when using signed formats.

             ` '     A space specifying that a blank should be left before a positive number for a signed
                     format.  A `+' overrides a space if both are used;

             0       A zero `0' character indicating that zero-padding should be used rather than blank-pad-ding. blank-padding.
                     ding.  A `-' overrides a `0' if both are used;

     Field Width:
             An optional digit string specifying a field width; if the output string has fewer characters
             than the field width it will be blank-padded on the left (or right, if the left-adjustment
             indicator has been given) to make up the field width (note that a leading zero is a flag, but
             an embedded zero is part of a field width);

     Precision:
             An optional period, `.', followed by an optional digit string giving a precision which speci-fies specifies
             fies the number of digits to appear after the decimal point, for e and f formats, or the maxi-mum maximum
             mum number of characters to be printed from a string; if the digit string is missing, the pre-cision precision
             cision is treated as zero;

     Format:
             A character which indicates the type of format to use (one of diouxXfFeEgGaAcsb).  The upper-case uppercase
             case formats differ from their lowercase counterparts only in that the output of the former is
             entirely in uppercase.  The floating-point format specifiers (fFeEgGaA) may be prefixed by an L
             to request that additional precision be used, if available.

     A field width or precision may be `*' instead of a digit string.  In this case an argument supplies the
     field width or precision.

     The format characters and their meanings are:

     diouXx      The argument is printed as a signed decimal (d or i), unsigned octal, unsigned decimal, or
                 unsigned hexadecimal (X or x), respectively.

     fF          The argument is printed in the style `[-]ddd.ddd' where the number of d's after the decimal
                 point is equal to the precision specification for the argument.  If the precision is miss-ing, missing,
                 ing, 6 digits are given; if the precision is explicitly 0, no digits and no decimal point
                 are printed.  The values infinity and NaN are printed as `inf' and `nan', respectively.

     eE          The argument is printed in the style e `[-d.ddd+-dd]' where there is one digit before the
                 decimal point and the number after is equal to the precision specification for the argu-ment; argument;
                 ment; when the precision is missing, 6 digits are produced.  The values infinity and NaN
                 are printed as `inf' and `nan', respectively.

     gG          The argument is printed in style f (F) or in style e (E) whichever gives full precision in
                 minimum space.

     aA          The argument is printed in style `[-h.hhh+-pd]' where there is one digit before the hexa-decimal hexadecimal
                 decimal point and the number after is equal to the precision specification for the argu-ment; argument;
                 ment; when the precision is missing, enough digits are produced to convey the argument's
                 exact double-precision floating-point representation.  The values infinity and NaN are
                 printed as `inf' and `nan', respectively.

     c           The first character of argument is printed.

     s           Characters from the string argument are printed until the end is reached or until the num-ber number
                 ber of characters indicated by the precision specification is reached; however if the pre-cision precision
                 cision is 0 or missing, all characters in the string are printed.

     b           As for s, but interpret character escapes in backslash notation in the string argument.

     %           Print a `%'; no argument is used.

     The decimal point character is defined in the program's locale (category LC_NUMERIC).

     In no case does a non-existent or small field width cause truncation of a field; padding takes place
     only if the specified field width exceeds the actual width.

EXIT STATUS
     The printf utility exits 0 on success, and >0 if an error occurs.

COMPATIBILITY
     The traditional BSD behavior of converting arguments of numeric formats not beginning with a digit to
     the ASCII code of the first character is not supported.

SEE ALSO
     echo(1), printf(3)

STANDARDS
     The printf command is expected to be mostly compatible with the IEEE Std 1003.2 (``POSIX.2'') specifi-cation. specification.
     cation.

HISTORY
     The printf command appeared in 4.3BSD-Reno.  It is modeled after the standard library function,
     printf(3).

BUGS
     Since the floating point numbers are translated from ASCII to floating-point and then back again,
     floating-point precision may be lost.  (By default, the number is translated to an IEEE-754 double-pre-cision double-precision
     cision value before being printed.  The L modifier may produce additional precision, depending on the
     hardware platform.)

     ANSI hexadecimal character constants were deliberately not provided.

     The escape sequence \000 is the string terminator.  When present in the argument for the b format, the
     argument will be truncated at the \000 character.

     Multibyte characters are not recognized in format strings (this is only a problem if `%' can appear
     inside a multibyte character).

     Parsing of - arguments is also somewhat different from printf(3), where unknown arguments are simply
     printed instead of being flagged as errors.

BSD                             April 14, 2005                             BSD

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