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



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

SYNOPSIS
       #define _XOPEN_SOURCE 500
       #include <time.h>

       struct tm *getdate(const char *string);

       extern int getdate_err;

       #define _GNU_SOURCE
       #include <time.h>

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

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 conse-
       quently 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 corre-
       sponding to the current local time (as by a call to localtime(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 func-
       tion 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 pro-
       gram:

           $ 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\n",
                          j, getdate_err);
                   continue;
               }

               printf("Call %d (\"%s\") succeeded:\n", j, argv[j]);
               printf("    tm_sec   = %d\n", tmp->tm_sec);
               printf("    tm_min   = %d\n", tmp->tm_min);
               printf("    tm_hour  = %d\n", tmp->tm_hour);
               printf("    tm_mday  = %d\n", tmp->tm_mday);
               printf("    tm_mon   = %d\n", tmp->tm_mon);
               printf("    tm_year  = %d\n", tmp->tm_year);
               printf("    tm_wday  = %d\n", tmp->tm_wday);
               printf("    tm_yday  = %d\n", tmp->tm_yday);
               printf("    tm_isdst = %d\n", 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 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



                                  2008-09-07                        GETDATE(3)