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


       #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)):

           _XOPEN_SOURCE >= 500


       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

       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.


       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


       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.


              File containing format patterns.

       TZ, LC_TIME
              Variables used by strptime(3).


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

       │InterfaceAttributeValue                             │
       │getdate()   │ Thread safety │ MT-Unsafe race:getdate env locale │
       │getdate_r() │ Thread safety │ MT-Safe env locale                │


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


       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.


       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>

       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);

               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);



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


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                                            2019-03-06                                 GETDATE(3)