getdate(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ENVIRONMENT | ATTRIBUTES | CONFORMING TO | NOTES | EXAMPLES | SEE ALSO | COLOPHON

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

NAME         top

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

SYNOPSIS         top

       #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
       getdate_r():
           _GNU_SOURCE

DESCRIPTION         top

       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 localtime(3)).

       When only the day of the week 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         top

       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         top

       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         top

       DATEMSK
              File containing format patterns.

       TZ, LC_TIME
              Variables used by strptime(3).

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌────────────┬───────────────┬───────────────────────────────────┐
       │Interface   Attribute     Value                             │
       ├────────────┼───────────────┼───────────────────────────────────┤
       │getdate()   │ Thread safety │ MT-Unsafe race:getdate env locale │
       ├────────────┼───────────────┼───────────────────────────────────┤
       │getdate_r() │ Thread safety │ MT-Safe env locale                │
       └────────────┴───────────────┴───────────────────────────────────┘

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008.

NOTES         top

       The POSIX.1 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.

EXAMPLES         top

       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 name of the day of the week
           $ 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
       #include <time.h>
       #include <stdio.h>
       #include <stdlib.h>

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

           for (int 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         top

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

COLOPHON         top

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                               2020-11-01                     GETDATE(3)

Pages that refer to this page: strptime(3)