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

PROLOG
       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
       getdate - convert user format date and time

SYNOPSIS
       #include <time.h>

       struct tm *getdate(const char *string);

DESCRIPTION
       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 is used by getdate() to
       return error values.

       Templates are used to parse and interpret the input  string.  The  tem‐
       plates are contained in a text file identified by the environment vari‐
       able 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  interpreta‐
       tion 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  IEEE Std 1003.1-2001
	      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()).

       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 whitespace 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 unspeci‐
       fied.

       The getdate() function need not be reentrant. A function	 that  is  not
       required to be reentrant is not required to be thread-safe.

RETURN VALUE
       Upon  successful	 completion,  getdate()	 shall	return	a pointer to a
       struct tm. Otherwise, it shall return  a	 null  pointer	and  set  get‐
       date_err to indicate the error.

ERRORS
       The  getdate() function shall fail in the following cases, setting get‐
       date_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
	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
       Although historical versions of getdate() did not require that <time.h>
       declare	 the   external	  variable   getdate_err,   this   volume   of
       IEEE Std 1003.1-2001 does require it. The standard developers encourage
       applications to remove declarations of getdate_err and instead incorpo‐
       rate the declaration by including <time.h>.

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

RATIONALE
       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
       None.

SEE ALSO
       ctime(), localtime(), setlocale(), strftime(), times(), the Base	 Defi‐
       nitions volume of IEEE Std 1003.1-2001, <time.h>

COPYRIGHT
       Portions	 of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating	System	Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003	by  the	 Institute  of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .

IEEE/The Open Group		     2003			   GETDATE(3P)
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