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STRFTIME(3)                Linux Programmer's Manual               STRFTIME(3)

NAME
       strftime - format date and time

SYNOPSIS
       #include <time.h>

       size_t strftime(char *s, size_t max, const char *format,
                           const struct tm *tm);

DESCRIPTION
       The strftime() function formats the broken-down time tm according to
       the format specification format and places the result in the character
       array s of size max.

       Ordinary characters placed in the format string are copied to s without
       conversion.  Conversion specifiers are introduced by a `%' character,
       and are replaced in s as follows:

       %a     The abbreviated weekday name according to the current locale.

       %A     The full weekday name according to the current locale.

       %b     The abbreviated month name according to the current locale.

       %B     The full month name according to the current locale.

       %c     The preferred date and time representation for the current
              locale.

       %C     The century number (year/100) as a 2-digit integer. (SU)

       %d     The day of the month as a decimal number (range 01 to 31).

       %D     Equivalent to %m/%d/%y. (Yecch - for Americans only.  Americans
              should note that in other countries %d/%m/%y is rather common.
              This means that in international context this format is
              ambiguous and should not be used.) (SU)

       %e     Like %d, the day of the month as a decimal number, but a leading
              zero is replaced by a space. (SU)

       %E     Modifier: use alternative format, see below. (SU)

       %F     Equivalent to %Y-%m-%d (the ISO 8601 date format). (C99)

       %G     The ISO 8601 year with century as a decimal number.  The 4-digit
              year corresponding to the ISO week number (see %V).  This has
              the same format and value as %y, except that if the ISO week
              number belongs to the previous or next year, that year is used
              instead. (TZ)

       %g     Like %G, but without century, i.e., with a 2-digit year (00-99).
              (TZ)

       %h     Equivalent to %b. (SU)

       %H     The hour as a decimal number using a 24-hour clock (range 00 to
              23).

       %I     The hour as a decimal number using a 12-hour clock (range 01 to
              12).

       %j     The day of the year as a decimal number (range 001 to 366).

       %k     The hour (24-hour clock) as a decimal number (range 0 to 23);
              single digits are preceded by a blank. (See also %H.) (TZ)

       %l     The hour (12-hour clock) as a decimal number (range 1 to 12);
              single digits are preceded by a blank. (See also %I.) (TZ)

       %m     The month as a decimal number (range 01 to 12).

       %M     The minute as a decimal number (range 00 to 59).

       %n     A newline character. (SU)

       %O     Modifier: use alternative format, see below. (SU)

       %p     Either `AM' or `PM' according to the given time value, or the
              corresponding strings for the current locale.  Noon is treated
              as `pm' and midnight as `am'.

       %P     Like %p but in lowercase: `am' or `pm' or a corresponding string
              for the current locale. (GNU)

       %r     The time in a.m. or p.m. notation.  In the POSIX locale this is
              equivalent to `%I:%M:%S %p'. (SU)

       %R     The time in 24-hour notation (%H:%M). (SU) For a version
              including the seconds, see %T below.

       %s     The number of seconds since the Epoch, i.e., since 1970-01-01
              00:00:00 UTC. (TZ)

       %S     The second as a decimal number (range 00 to 61).

       %t     A tab character. (SU)

       %T     The time in 24-hour notation (%H:%M:%S). (SU)

       %u     The day of the week as a decimal, range 1 to 7, Monday being 1.
              See also %w. (SU)

       %U     The week number of the current year as a decimal number, range
              00 to 53, starting with the first Sunday as the first day of
              week 01. See also %V and %W.

       %V     The ISO 8601:1988 week number of the current year as a decimal
              number, range 01 to 53, where week 1 is the first week that has
              at least 4 days in the current year, and with Monday as the
              first day of the week. See also %U and %W. (SU)

       %w     The day of the week as a decimal, range 0 to 6, Sunday being 0.
              See also %u.

       %W     The week number of the current year as a decimal number, range
              00 to 53, starting with the first Monday as the first day of
              week 01.

       %x     The preferred date representation for the current locale without
              the time.

       %X     The preferred time representation for the current locale without
              the date.

       %y     The year as a decimal number without a century (range 00 to 99).

       %Y     The year as a decimal number including the century.

       %z     The time-zone as hour offset from GMT.  Required to emit
              RFC822-conformant dates (using "%a, %d %b %Y %H:%M:%S %z").
              (GNU)

       %Z     The time zone or name or abbreviation.

       %+     The date and time in date(1) format. (TZ)

       %%     A literal `%' character.

       Some conversion specifiers can be modified by preceding them by the E
       or O modifier to indicate that an alternative format should be used.
       If the alternative format or specification does not exist for the
       current locale, the behaviour will be as if the unmodified conversion
       specification were used. (SU) The Single Unix Specification mentions
       %Ec, %EC, %Ex, %EX, %Ry, %EY, %Od, %Oe, %OH, %OI, %Om, %OM, %OS, %Ou,
       %OU, %OV, %Ow, %OW, %Oy, where the effect of the O modifier is to use
       alternative numeric symbols (say, roman numerals), and that of the E
       modifier is to use a locale-dependent alternative representation.

       The broken-down time structure tm is defined in _time.h_.  See also
       ctime(3).

RETURN VALUE
       The strftime() function returns the number of characters placed in the
       array s, not including the terminating NUL character, provided the
       string, including the terminating NUL, fits.  Otherwise, it returns 0,
       and the contents of the array is undefined.  (Thus at least since libc
       4.4.4; very old versions of libc, such as libc 4.4.1, would return max
       if the array was too small.)

       Note that the return value 0 does not necessarily indicate an error;
       for example, in many locales %p yields an empty string.

ENVIRONMENT
       The environment variables TZ and LC_TIME are used.

CONFORMING TO
       ANSI C, SVID 3, ISO 9899.  There are strict inclusions between the set
       of conversions given in ANSI C (unmarked), those given in the Single
       Unix Specification (marked SU), those given in Olson's timezone package
       (marked TZ), and those given in glibc (marked GNU), except that %+ is
       not supported in glibc2. On the other hand glibc2 has several more
       extensions.  POSIX.1 only refers to ANSI C; POSIX.2 describes under
       date(1) several extensions that could apply to strftime as well.  The
       %F conversion is in C99 and POSIX 1003.1-2001.

SEE ALSO
       date(1), time(2), ctime(3), setlocale(3), sprintf(3)

GNU                               1999-03-29                       STRFTIME(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ENVIRONMENT | CONFORMING TO | SEE ALSO

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