GETDATE(3) Linux Programmers Manual GETDATE(3)
getdate, getdate_r - convert a string to struct tm
#define _XOPEN_SOURCE 500
struct tm *getdate(const char *string);
extern int getdate_err;
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 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 accepted:
%Z Timezone name.
When %Z is given, the value to be returned is initialized to the bro
ken-down time corresponding to the current time in the given time zone.
Otherwise, it is initialized 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. Oth
erwise, it returns NULL and sets the global variable getdate_err.
Changes to errno are unspecified. The following values for getdate_err
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 error is 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.
Variables used by strptime(3).
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
non-zero with the same values as given above for getdate_err.
The POSIX.1-2001 specification for strptime(3) contains conversion
specifications using the %E or %O modifier, while such specifications
are not given for getdate(). The glibc implementation implements get
date() using strptime(3) so that automatically precisely the same con
versions are supported by both.
The glibc implementation does not support the %Z conversion specifica
time(2), localtime(3), setlocale(3), strftime(3), strptime(3), fea
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