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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ENVIRONMENT | ATTRIBUTES | VERSIONS | STANDARDS | HISTORY | EXAMPLES | SEE ALSO | COLOPHON |
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getdate(3) Library Functions Manual getdate(3)
getdate, getdate_r - convert a date-plus-time string to broken-
down time
Standard C library (libc, -lc)
#include <time.h>
struct tm *getdate(const char *string);
extern int getdate_err;
int getdate_r(const char *restrict string, struct tm *restrict res);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
getdate():
_XOPEN_SOURCE >= 500
getdate_r():
_GNU_SOURCE
The function getdate() converts a string representation of a date
and time, contained in the buffer pointed to by string, into a
broken-down time. The broken-down time is stored in a tm
structure, and a pointer to this structure is returned as the
function result. This tm structure is allocated in static
storage, and consequently it will be overwritten by further calls
to getdate().
In contrast to strptime(3), (which has a format argument),
getdate() uses the formats found in the file whose 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 specified in POSIX.1-2001:
%Z Timezone name. This is not implemented in glibc.
When %Z is given, the structure containing the broken-down time
is initialized with values corresponding to the current time in
the given timezone. Otherwise, the structure is initialized to
the broken-down time corresponding to the current local time (as
by a call to localtime(3)).
When only the day of the week 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.
getdate_r() is a GNU extension that provides a reentrant version
of getdate(). Rather than using a global variable to report
errors and a static buffer to return the broken down time, it
returns errors via the function result value, and returns the
resulting broken-down time in the caller-allocated buffer pointed
to by the argument res.
When successful, getdate() returns a pointer to a struct tm.
Otherwise, it returns NULL and sets the global variable
getdate_err to one of the error numbers shown below. Changes to
errno are unspecified.
On success getdate_r() returns 0; on error it returns one of the
error numbers shown below.
The following errors are returned via getdate_err (for getdate())
or as the function result (for getdate_r()):
1 The DATEMSK environment variable is not defined, or its value
is an empty string.
2 The template file specified by DATEMSK cannot be opened for
reading.
3 Failed to get file status information.
4 The template file is not a regular file.
5 An error was 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.
DATEMSK
File containing format patterns.
TZ
LC_TIME
Variables used by strptime(3).
For an explanation of the terms used in this section, see
attributes(7).
┌─────────────┬───────────────┬─────────────────────────────────┐
│ Interface │ Attribute │ Value │
├─────────────┼───────────────┼─────────────────────────────────┤
│ getdate() │ Thread safety │ MT-Unsafe race:getdate env │
│ │ │ locale │
├─────────────┼───────────────┼─────────────────────────────────┤
│ getdate_r() │ Thread safety │ MT-Safe env locale │
└─────────────┴───────────────┴─────────────────────────────────┘
The POSIX.1 specification for strptime(3) contains conversion
specifications using the %E or %O modifier, while such
specifications are not given for getdate(). In glibc, getdate()
is implemented using strptime(3), so that precisely the same
conversions are supported by both.
POSIX.1-2008.
POSIX.1-2001.
The program below calls getdate() for each of its command-line
arguments, and for each call displays the values in the fields of
the returned tm structure. The following shell session
demonstrates the operation of the program:
$ TFILE=$PWD/tfile
$ echo '%A' > $TFILE # Full name of the day of the week
$ echo '%T' >> $TFILE # Time (HH:MM:SS)
$ echo '%F' >> $TFILE # ISO date (YYYY-MM-DD)
$ date
$ export DATEMSK=$TFILE
$ ./a.out Tuesday '2009-12-28' '12:22:33'
Sun Sep 7 06:03:36 CEST 2008
Call 1 ("Tuesday") succeeded:
tm_sec = 36
tm_min = 3
tm_hour = 6
tm_mday = 9
tm_mon = 8
tm_year = 108
tm_wday = 2
tm_yday = 252
tm_isdst = 1
Call 2 ("2009-12-28") succeeded:
tm_sec = 36
tm_min = 3
tm_hour = 6
tm_mday = 28
tm_mon = 11
tm_year = 109
tm_wday = 1
tm_yday = 361
tm_isdst = 0
Call 3 ("12:22:33") succeeded:
tm_sec = 33
tm_min = 22
tm_hour = 12
tm_mday = 7
tm_mon = 8
tm_year = 108
tm_wday = 0
tm_yday = 250
tm_isdst = 1
Program source
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int
main(int argc, char *argv[])
{
struct tm *tmp;
for (size_t j = 1; j < argc; j++) {
tmp = getdate(argv[j]);
if (tmp == NULL) {
printf("Call %zu failed; getdate_err = %d\n",
j, getdate_err);
continue;
}
printf("Call %zu (\"%s\") succeeded:\n", j, argv[j]);
printf(" tm_sec = %d\n", tmp->tm_sec);
printf(" tm_min = %d\n", tmp->tm_min);
printf(" tm_hour = %d\n", tmp->tm_hour);
printf(" tm_mday = %d\n", tmp->tm_mday);
printf(" tm_mon = %d\n", tmp->tm_mon);
printf(" tm_year = %d\n", tmp->tm_year);
printf(" tm_wday = %d\n", tmp->tm_wday);
printf(" tm_yday = %d\n", tmp->tm_yday);
printf(" tm_isdst = %d\n", tmp->tm_isdst);
}
exit(EXIT_SUCCESS);
}
time(2), localtime(3), setlocale(3), strftime(3), strptime(3)
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Linux man-pages 6.9.1 2024-06-15 getdate(3)
Pages that refer to this page: strptime(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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