getdate_r(3) -- Linux man page



getdate() - convert a string to struct tm


#include <time.h>

struct tm *getdate (const char *string);

extern int getdate_err;

#define _GNU_SOURCE
#include <time.h>

int getdate_r (const char *string, struct tm *res);


The function getdate() converts a string pointed to by string into the tm structure that it returns. This tm structure may be found in static storage, so that it will be overwritten by the next call.

In contrast to strptime(3), (which has a format argument), getdate() uses the formats found in the file of which the full path name 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 accepted:

Timezone name.

When %Z is given, the value to be returned is initialised to the broken-down time corresponding to the current time in the given time zone. Otherwise, it is initialised to the broken-down time corresponding to the current local time.

When only the weekday 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.  


When successful, this function returns a pointer to a struct tm. Otherwise, it returns NULL and sets the global variable getdate_err. Changes to errno are unspecified. The following values for getdate_err are defined:
The DATEMSK environment variable is null or undefined.
The template file cannot be opened for reading.
Failed to get file status information.
The template file is not a regular file.
An error is encountered while reading the template file.
Memory allocation failed (not enough memory available).
There is no line in the file that matches the input.
Invalid input specification.


Since getdate() is not reentrant because of the use of getdate_err and the static buffer to return the result in, glibc provides a thread-safe variant. The functionality is the same. The result is returned in the buffer pointed to by res and in case of an error the return value is nonzero with the same values as given above for getdate_err.

The POSIX 1003.1-2001 specification for strptime() contains conversion specifications using the %E or %O modifier, while such specifications are not given for getdate(). The glibc implementation implements getdate() using strptime() so that automatically precisely the same conversions are supported by both.

The glibc implementation does not support the %Z conversion specification.  


File containing format patterns.
Variables used by strptime().


ISO 9899, POSIX 1003.1-2001  


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