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PRINTF(1)               FreeBSD 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:

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

     The format string is reused as often as necessary to satisfy the
     arguments.  Any extra format specifications 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    Write a byte whose value is the 1-, 2-, or 3-digit octal
                   number num.  Multibyte characters can be constructed using
                   multiple \num sequences.

     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 b, c, d, s and u
                     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 a, A, e, E, f, 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-padding.  A `-' overrides a `0'
                     if both are used;

     Field Width:
             An optional digit string specifying a field width; if the output
             string has fewer bytes 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 specifies the number of digits to appear
             after the decimal point, for e and f formats, or the maximum
             number of bytes to be printed from a string; if the digit string
             is missing, the precision is treated as zero;

     Format:
             A character which indicates the type of format to use (one of
             diouxXfFeEgGaAcsb).  The uppercase 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 missing, 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
                 argument; 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 hexadecimal point and the number
                 after is equal to the precision specification for the
                 argument; 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 byte of argument is printed.

     s           Bytes from the string argument are printed until the end is
                 reached or until the number of bytes indicated by the
                 precision specification is reached; however if the precision
                 is 0 or missing, the string is printed entirely.

     b           As for s, but interpret character escapes in backslash
                 notation in the string argument.  The permitted escape
                 sequences are slightly different in that octal escapes are
                 \0num instead of \num.

     %           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.

     Some shells may provide a builtin printf command which is similar or
     identical to this utility.  Consult the builtin(1) manual page.

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
     builtin(1), echo(1), sh(1), printf(3)

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

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

CAVEATS
     ANSI hexadecimal character constants were deliberately not provided.

     Trying to print a dash ("-") as the first character causes printf to
     interpret the dash as a program argument.  -- must be used before format.

     If the locale contains multibyte characters (such as UTF-8), the c format
     and b and s formats with a precision may not operate as expected.

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-precision value
     before being printed.  The L modifier may produce additional precision,
     depending on the hardware platform.)

     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).

FreeBSD 11.0-PRERELEASE          May 28, 2011          FreeBSD 11.0-PRERELEASE

NAME | SYNOPSIS | DESCRIPTION | EXIT STATUS | COMPATIBILITY | SEE ALSO | STANDARDS | HISTORY | CAVEATS | BUGS

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