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

NAME

       getdate, getdate_r - convert a date-plus-time string to broken-down time

SYNOPSIS

       #include <time.h>

       struct tm *getdate(const char *string);

       extern int getdate_err;

       #include <time.h>

       int getdate_r(const char *string, struct tm *res);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getdate():
	   _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
       getdate_r():
	   _GNU_SOURCE

DESCRIPTION

       The  function  getdate()  converts a string representation of a date and time, contained in the buffer pointed to by string, into a broken-
       down time.  The broken-down time is stored in a tm structure, and a pointer to this structure is returned as the function result.  This	tm
       structure is allocated in static storage, and consequently it will be overwritten by further calls to getdate().

       In contrast to strptime(3), (which has a format argument), getdate() uses the formats found in the file whose full pathname is given in the
       environment variable DATEMSK.  The first line in the file that matches the given input string is used for the conversion.

       The matching is done case insensitively.  Superfluous whitespace, either in the pattern or in the string to be converted, is ignored.

       The conversion specifications that a pattern can contain are those given for strptime(3).  One more conversion specification  is  specified
       in POSIX.1-2001:

       %Z     Timezone name.  This is not implemented in glibc.

       When  %Z  is given, the structure containing the broken-down time is initialized with values corresponding to the current time in the given
       timezone.  Otherwise, the structure is initialized to the broken-down time corresponding to the current local time (as by a call to  local-
       time(3)).

       When only the weekday is given, the day is taken to be the first such day on or after today.

       When  only  the month is given (and no year), the month is taken to be the first such month equal to or after the current month.  If no day
       is given, it is the first day of the month.

       When no hour, minute and second are given, the current hour, minute and second are taken.

       If no date is given, but we know the hour, then that hour is taken to be the first such hour equal to or after the current hour.

       getdate_r() is a GNU extension that provides a reentrant version of getdate().  Rather than using a global variable to report errors and  a
       static  buffer  to return the broken down time, it returns errors via the function result value, and returns the resulting broken-down time
       in the caller-allocated buffer pointed to by the argument res.

RETURN VALUE

       When successful, getdate() returns a pointer to a struct tm.  Otherwise, it returns NULL and sets the global variable getdate_err to one of
       the error numbers shown below.  Changes to errno are unspecified.

       On success getdate_r() returns 0; on error it returns one of the error numbers shown below.

ERRORS

       The following errors are returned via getdate_err (for getdate()) or as the function result (for getdate_r()):

       1   The DATEMSK environment variable is not defined, or its value is an empty string.

       2   The template file specified by DATEMSK cannot be opened for reading.

       3   Failed to get file status information.

       4   The template file is not a regular file.

       5   An error was encountered while reading the template file.

       6   Memory allocation failed (not enough memory available).

       7   There is no line in the file that matches the input.

       8   Invalid input specification.

ENVIRONMENT

       DATEMSK
	      File containing format patterns.

       TZ, LC_TIME
	      Variables used by strptime(3).

CONFORMING TO

       POSIX.1-2001.

NOTES

       The  POSIX.1-2001  specification  for strptime(3) contains conversion specifications using the %E or %O modifier, while such specifications
       are not given for getdate().  In glibc, getdate() is implemented using strptime(3), so that precisely the same conversions are supported by
       both.

EXAMPLE

       The  program  below  calls  getdate()  for  each  of its command-line arguments, and for each call displays the values in the fields of the
       returned tm structure.  The following shell session demonstrates the operation of the program:

	   $ TFILE=$PWD/tfile
	   $ echo '%A' > $TFILE       # Full weekday name
	   $ echo '%T' >> $TFILE      # ISO date (YYYY-MM-DD)
	   $ echo '%F' >> $TFILE      # Time (HH:MM:SS)
	   $ date
	   $ export DATEMSK=$TFILE
	   $ ./a.out Tuesday '2009-12-28' '12:22:33'
	   Sun Sep  7 06:03:36 CEST 2008
	   Call 1 ("Tuesday") succeeded:
	       tm_sec	= 36
	       tm_min	= 3
	       tm_hour	= 6
	       tm_mday	= 9
	       tm_mon	= 8
	       tm_year	= 108
	       tm_wday	= 2
	       tm_yday	= 252
	       tm_isdst = 1
	   Call 2 ("2009-12-28") succeeded:
	       tm_sec	= 36
	       tm_min	= 3
	       tm_hour	= 6
	       tm_mday	= 28
	       tm_mon	= 11
	       tm_year	= 109
	       tm_wday	= 1
	       tm_yday	= 361
	       tm_isdst = 0
	   Call 3 ("12:22:33") succeeded:
	       tm_sec	= 33
	       tm_min	= 22
	       tm_hour	= 12
	       tm_mday	= 7
	       tm_mon	= 8
	       tm_year	= 108
	       tm_wday	= 0
	       tm_yday	= 250
	       tm_isdst = 1

   Program source

       #define _GNU_SOURCE 500
       #include <time.h>
       #include <stdio.h>
       #include <stdlib.h>

       int
       main(int argc, char *argv[])
       {
	   struct tm *tmp;
	   int j;

	   for (j = 1; j < argc; j++) {
	       tmp = getdate(argv[j]);

	       if (tmp == NULL) {
		   printf("Call %d failed; getdate_err = %d
",
			  j, getdate_err);
		   continue;
	       }

	       printf("Call %d ("%s") succeeded:
", j, argv[j]);
	       printf("    tm_sec   = %d
", tmp->tm_sec);
	       printf("    tm_min   = %d
", tmp->tm_min);
	       printf("    tm_hour  = %d
", tmp->tm_hour);
	       printf("    tm_mday  = %d
", tmp->tm_mday);
	       printf("    tm_mon   = %d
", tmp->tm_mon);
	       printf("    tm_year  = %d
", tmp->tm_year);
	       printf("    tm_wday  = %d
", tmp->tm_wday);
	       printf("    tm_yday  = %d
", tmp->tm_yday);
	       printf("    tm_isdst = %d
", tmp->tm_isdst);
	   }

	   exit(EXIT_SUCCESS);
       }

SEE ALSO

       time(2), localtime(3), setlocale(3), strftime(3), strptime(3), feature_test_macros(7)

COLOPHON

       This page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

								    2010-09-20								GETDATE(3)