PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

GETDATE(3P)               POSIX Programmer's Manual              GETDATE(3P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       getdate — convert user format date and time

SYNOPSIS         top

       #include <time.h>

       struct tm *getdate(const char *string);

DESCRIPTION         top

       The getdate() function shall convert a string representation of a
       date or time into a broken-down time.

       The external variable or macro getdate_err, which has type int, is
       used by getdate() to return error values. It is unspecified whether
       getdate_err is a macro or an identifier declared with external
       linkage, and whether or not it is a modifiable lvalue. If a macro
       definition is suppressed in order to access an actual object, or a
       program defines an identifier with the name getdate_err, the behavior
       is undefined.

       Templates are used to parse and interpret the input string. The
       templates are contained in a text file identified by the environment
       variable DATEMSK.  The DATEMSK variable should be set to indicate the
       full pathname of the file that contains the templates. The first line
       in the template that matches the input specification is used for
       interpretation and conversion into the internal time format.

       The following conversion specifications shall be supported:

       %%      Equivalent to %.

       %a      Abbreviated weekday name.

       %A      Full weekday name.

       %b      Abbreviated month name.

       %B      Full month name.

       %c      Locale's appropriate date and time representation.

       %C      Century number [00,99]; leading zeros are permitted but not
               required.

       %d      Day of month [01,31]; the leading 0 is optional.

       %D      Date as %m/%d/%y.

       %e      Equivalent to %d.

       %h      Abbreviated month name.

       %H      Hour [00,23].

       %I      Hour [01,12].

       %m      Month number [01,12].

       %M      Minute [00,59].

       %n      Equivalent to <newline>.

       %p      Locale's equivalent of either AM or PM.

       %r      The locale's appropriate representation of time in AM and PM
               notation.  In the POSIX locale, this shall be equivalent to
               %I:%M:%S %p.

       %R      Time as %H:%M.

       %S      Seconds [00,60]. The range goes to 60 (rather than stopping
               at 59) to allow positive leap seconds to be expressed. Since
               leap seconds cannot be predicted by any algorithm, leap
               second data must come from some external source.

       %t      Equivalent to <tab>.

       %T      Time as %H:%M:%S.

       %w      Weekday number (Sunday = [0,6]).

       %x      Locale's appropriate date representation.

       %X      Locale's appropriate time representation.

       %y      Year within century. When a century is not otherwise
               specified, values in the range [69,99] shall refer to years
               1969 to 1999 inclusive, and values in the range [00,68] shall
               refer to years 2000 to 2068 inclusive.

               Note:     It is expected that in a future version of this
                         standard the default century inferred from a
                         2-digit year will change. (This would apply to all
                         commands accepting a 2-digit year as input.)

       %Y      Year as "ccyy" (for example, 2001).

       %Z      Timezone name or no characters if no timezone exists. If the
               timezone supplied by %Z is not the timezone that getdate()
               expects, an invalid input specification error shall result.
               The getdate() function calculates an expected timezone based
               on information supplied to the function (such as the hour,
               day, and month).

       The match between the template and input specification performed by
       getdate() shall be case-insensitive.

       The month and weekday names can consist of any combination of upper
       and lowercase letters. The process can request that the input date or
       time specification be in a specific language by setting the LC_TIME
       category (see setlocale(3p)).

       Leading zeros are not necessary for the descriptors that allow
       leading zeros. However, at most two digits are allowed for those
       descriptors, including leading zeros. Extra white space in either the
       template file or in string shall be ignored.

       The results are undefined if the conversion specifications %c, %x,
       and %X include unsupported conversion specifications.

       The following rules apply for converting the input specification into
       the internal format:

        *  If %Z is being scanned, then getdate() shall initialize the
           broken-down time to be the current time in the scanned timezone.
           Otherwise, it shall initialize the broken-down time based on the
           current local time as if localtime() had been called.

        *  If only the weekday is given, the day chosen shall be the day,
           starting with today and moving into the future, which first
           matches the named day.

        *  If only the month (and no year) is given, the month chosen shall
           be the month, starting with the current month and moving into the
           future, which first matches the named month. The first day of the
           month shall be assumed if no day is given.

        *  If no hour, minute, and second are given, the current hour,
           minute, and second shall be assumed.

        *  If no date is given, the hour chosen shall be the hour, starting
           with the current hour and moving into the future, which first
           matches the named hour.

       If a conversion specification in the DATEMSK file does not correspond
       to one of the conversion specifications above, the behavior is
       unspecified.

       The getdate() function need not be thread-safe.

RETURN VALUE         top

       Upon successful completion, getdate() shall return a pointer to a
       struct tm.  Otherwise, it shall return a null pointer and set
       getdate_err to indicate the error.

ERRORS         top

       The getdate() function shall fail in the following cases, setting
       getdate_err to the value shown in the list below. Any changes to
       errno are unspecified.

        1. The DATEMSK environment variable is null or undefined.

        2. The template file cannot be opened for reading.

        3. Failed to get file status information.

        4. The template file is not a regular file.

        5. An I/O error is encountered while reading the template file.

        6. Memory allocation failed (not enough memory available).

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

        8. Invalid input specification. For example, February 31; or a time
           is specified that cannot be represented in a time_t (representing
           the time in seconds since the Epoch).

       The following sections are informative.

EXAMPLES         top

        1. The following example shows the possible contents of a template:

               %m
               %A %B %d, %Y, %H:%M:%S
               %A
               %B
               %m/%d/%y %I %p
               %d,%m,%Y %H:%M
               at %A the %dst of %B in %Y
               run job at %I %p,%B %dnd
               %A den %d. %B %Y %H.%M Uhr

        2. The following are examples of valid input specifications for the
           template in Example 1:

               getdate("10/1/87 4 PM");
               getdate("Friday");
               getdate("Friday September 18, 1987, 10:30:30");
               getdate("24,9,1986 10:30");
               getdate("at monday the 1st of december in 1986");
               getdate("run job at 3 PM, december 2nd");

           If the LC_TIME category is set to a German locale that includes
           freitag as a weekday name and oktober as a month name, the
           following would be valid:

               getdate("freitag den 10. oktober 1986 10.30 Uhr");

        3. The following example shows how local date and time specification
           can be defined in the template:

                    ┌───────────────────────────┬──────────────────┐
                    │        Invocation         Line in Template │
                    ├───────────────────────────┼──────────────────┤
                    │getdate("11/27/86")        │ %m/%d/%y         │
                    │getdate("27.11.86")        │ %d.%m.%y         │
                    │getdate("86-11-27")        │ %y-%m-%d         │
                    │getdate("Friday 12:00:00") │ %A %H:%M:%S      │
                    └───────────────────────────┴──────────────────┘
        4. The following examples help to illustrate the above rules
           assuming that the current date is Mon Sep 22 12:19:47 EDT 1986
           and the LC_TIME category is set to the default C locale:

           ┌─────────────┬──────────────────┬──────────────────────────────┐
           │   Input     Line in Template Date             │
           ├─────────────┼──────────────────┼──────────────────────────────┤
           │Mon          │ %a               │ Mon Sep 22 12:19:47 EDT 1986 │
           │Sun          │ %a               │ Sun Sep 28 12:19:47 EDT 1986 │
           │Fri          │ %a               │ Fri Sep 26 12:19:47 EDT 1986 │
           │September    │ %B               │ Mon Sep 1 12:19:47 EDT 1986  │
           │January      │ %B               │ Thu Jan 1 12:19:47 EST 1987  │
           │December     │ %B               │ Mon Dec 1 12:19:47 EST 1986  │
           │Sep Mon      │ %b %a            │ Mon Sep 1 12:19:47 EDT 1986  │
           │Jan Fri      │ %b %a            │ Fri Jan 2 12:19:47 EST 1987  │
           │Dec Mon      │ %b %a            │ Mon Dec 1 12:19:47 EST 1986  │
           │Jan Wed 1989 │ %b %a %Y         │ Wed Jan 4 12:19:47 EST 1989  │
           │Fri 9        │ %a %H            │ Fri Sep 26 09:00:00 EDT 1986 │
           │Feb 10:30    │ %b %H:%S         │ Sun Feb 1 10:00:30 EST 1987  │
           │10:30        │ %H:%M            │ Tue Sep 23 10:30:00 EDT 1986 │
           │13:30        │ %H:%M            │ Mon Sep 22 13:30:00 EDT 1986 │
           └─────────────┴──────────────────┴──────────────────────────────┘

APPLICATION USAGE         top

       Although historical versions of getdate() did not require that
       <time.h> declare the external variable getdate_err, this volume of
       POSIX.1‐2008 does require it. The standard developers encourage
       applications to remove declarations of getdate_err and instead
       incorporate the declaration by including <time.h>.

       Applications should use %Y (4-digit years) in preference to %y
       (2-digit years).

RATIONALE         top

       In standard locales, the conversion specifications %c, %x, and %X do
       not include unsupported conversion specifiers and so the text
       regarding results being undefined is not a problem in that case.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       ctime(3p), localtime(3p), setlocale(3p), strftime(3p), times(3p)

       The Base Definitions volume of POSIX.1‐2008, time.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) In the event of any discrepancy between this version and
       the original IEEE and The Open Group Standard, the original IEEE and
       The Open Group Standard is the referee document. The original
       Standard can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                         GETDATE(3P)

Pages that refer to this page: time.h(0p)localtime(3p)strftime(3p)