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 correspond-
       ing 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 templates 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 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 sec-
	      onds 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 inclu-
	      sive, 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 descrip-
       tors, 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
       unspecified.

       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 getdate_err
       to indicate the error.

ERRORS

       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

	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
       incorporate 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  regard-
       ing results being undefined is not a problem in that case.

FUTURE DIRECTIONS

       None.

SEE ALSO

       ctime(), localtime(), setlocale(), strftime(), times(), the Base Definitions 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 Technol-
       ogy -- 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)