-.\" Copyright 2001 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\" Copyright 2001 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\" <mtk.manpages@gmail.com>
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
-.\"
+.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
-.\"
+.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
.\" Modified, 2001-12-26, aeb
-.TH GETDATE 3 2001-12-26 "" "Linux Programmer's Manual"
+.\" 2008-09-07, mtk, Various rewrites; added an example program.
+.\"
+.TH GETDATE 3 2019-03-06 "" "Linux Programmer's Manual"
.SH NAME
-getdate \- convert a string to struct tm
-.br
+getdate, getdate_r \- convert a date-plus-time string to broken-down time
.SH SYNOPSIS
-.B "#define _XOPEN_SOURCE"
-.br
-.B "#define _XOPEN_SOURCE_EXTENDED
-.br
.B "#include <time.h>"
-.sp
-.BI "struct tm *getdate (const char *" string );
-.sp
-.BI "extern int getdate_err;"
-.sp 2
-.B "#define _GNU_SOURCE"
-.br
+.PP
+.BI "struct tm *getdate(const char *" string );
+.PP
+.B "extern int getdate_err;"
+.PP
.B "#include <time.h>"
-.sp
-.BI "int getdate_r (const char *" string ", struct tm *" res );
+.PP
+.BI "int getdate_r(const char *" string ", struct tm *" res );
+.PP
+.in -4n
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.in
+.PP
+.BR getdate ():
+.ad l
+.RS 4
+_XOPEN_SOURCE\ >=\ 500
+.\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
+.RE
.br
+.BR getdate_r ():
+.ad l
+.RS 4
+_GNU_SOURCE
+.RE
+.ad
.SH DESCRIPTION
The function
.BR getdate ()
-converts a string pointed to by
-.I 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
+converts a string representation of a date and time,
+contained in the buffer pointed to by
+.IR string ,
+into a broken-down time.
+The broken-down time is stored in a
+.I tm
+structure, and a pointer to this
+structure is returned as the function result.
+This
+.I tm
+structure is allocated in static storage,
+and consequently it will be overwritten by further calls to
+.BR getdate ().
+.PP
+In contrast to
.BR strptime (3),
(which has a
.I format
argument),
.BR getdate ()
uses the formats found in the file
-of which the full path name is given in the environment variable
+whose full pathname is given in the environment variable
.BR DATEMSK .
The first line in the file that matches the given input string
is used for the conversion.
-
+.PP
The matching is done case insensitively.
Superfluous whitespace, either in the pattern or in the string to
be converted, is ignored.
-
+.PP
The conversion specifications that a pattern can contain are those given for
.BR strptime (3).
-One more conversion specification is accepted:
+One more conversion specification is specified in POSIX.1-2001:
.TP
.B %Z
Timezone name.
-.LP
+.\" FIXME Is it (still) true that %Z is not supported in glibc?
+.\" Looking at the glibc 2.21 source code, where the implementation uses
+.\" strptime(), suggests that it might be supported.
+This is not implemented in glibc.
+.PP
When
.B %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.
-.LP
-When only the weekday is given, the day is taken to be the first such day
+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
+.BR localtime (3)).
+.PP
+When only the day of the week is given,
+the day is taken to be the first such day
on or after today.
-.LP
+.PP
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.
-.LP
+.PP
When no hour, minute and second are given, the current
hour, minute and second are taken.
-.LP
+.PP
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.
-.SH "RETURN VALUE"
-When successful, this function returns a pointer to a
-.BR "struct tm" .
+.PP
+.BR getdate_r ()
+is a GNU extension that provides a reentrant version of
+.BR 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
+.IR res .
+.SH RETURN VALUE
+When successful,
+.BR getdate ()
+returns a pointer to a
+.IR "struct tm" .
Otherwise, it returns NULL and sets the global variable
-.BR getdate_err .
+.IR getdate_err
+to one of the error numbers shown below.
Changes to
.I errno
-are unspecified. The following values for
-.B getdate_err
-are defined:
+are unspecified.
+.PP
+On success
+.BR getdate_r ()
+returns 0;
+on error it returns one of the error numbers shown below.
+.SH ERRORS
+The following errors are returned via
+.IR getdate_err
+(for
+.BR getdate ())
+or as the function result (for
+.BR getdate_r ()):
.TP 4n
.B 1
-The DATEMSK environment variable is null or undefined.
+The
+.B DATEMSK
+environment variable is not defined, or its value is an empty string.
.TP
.B 2
-The template file cannot be opened for reading.
+The template file specified by
+.B DATEMSK
+cannot be opened for reading.
.TP
.B 3
Failed to get file status information.
+.\" stat()
.TP
.B 4
The template file is not a regular file.
.TP
.B 5
-An error is encountered while reading the template file.
+An error was encountered while reading the template file.
.TP
.B 6
Memory allocation failed (not enough memory available).
+.\" Error 6 doesn't seem to occur in glibc
.TP
.B 7
There is no line in the file that matches the input.
.TP
.B 8
Invalid input specification.
-.SH NOTES
-Since
+.SH ENVIRONMENT
+.TP
+.B DATEMSK
+File containing format patterns.
+.TP
+.BR TZ ", " LC_TIME
+Variables used by
+.BR strptime (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lb
+l l l.
+Interface Attribute Value
+T{
.BR getdate ()
-is not reentrant because of the use of
-.B 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
-.I res
-and in case of an error the return value is non-zero with the same
-values as given above for
-.IR getdate_err .
-.LP
-The POSIX 1003.1-2001 specification for
-.BR strptime ()
+T} Thread safety MT-Unsafe race:getdate env locale
+T{
+.BR getdate_r ()
+T} Thread safety MT-Safe env locale
+.TE
+.SH CONFORMING TO
+POSIX.1-2001, POSIX.1-2008.
+.SH NOTES
+The POSIX.1 specification for
+.BR strptime (3)
contains conversion specifications using the
.B %E
or
.B %O
modifier, while such specifications are not given for
.BR getdate ().
-The glibc implementation implements
+In glibc,
.BR getdate ()
-using
-.BR strptime ()
-so that automatically precisely the same conversions are supported by both.
-.LP
-The glibc implementation does not support the
-.B %Z
-conversion specification.
-.SH ENVIRONMENT
-.TP
-.B DATEMSK
-File containing format patterns.
-.TP
-.BR TZ ", " LC_TIME
-Variables used by \fBstrptime\fP().
-.SH "CONFORMING TO"
-ISO 9899, POSIX 1003.1-2001
-.SH "SEE ALSO"
+is implemented using
+.BR strptime (3),
+so that precisely the same conversions are supported by both.
+.SH EXAMPLES
+The program below calls
+.BR getdate ()
+for each of its command-line arguments,
+and for each call displays the values in the fields of the returned
+.I tm
+structure.
+The following shell session demonstrates the operation of the program:
+.PP
+.in +4n
+.EX
+.RB "$" " TFILE=$PWD/tfile"
+.RB "$" " echo \(aq%A\(aq > $TFILE " " # Full name of the day of the week"
+.RB "$" " echo \(aq%T\(aq >> $TFILE" " # ISO date (YYYY-MM-DD)"
+.RB "$" " echo \(aq%F\(aq >> $TFILE" " # Time (HH:MM:SS)"
+.RB "$" " date"
+.RB "$" " export DATEMSK=$TFILE"
+.RB "$" " ./a.out Tuesday \(aq2009-12-28\(aq \(aq12:22:33\(aq"
+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
+.EE
+.in
+.SS Program source
+\&
+.EX
+#define _GNU_SOURCE
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int
+main(int argc, char *argv[])
+{
+ struct tm *tmp;
+ int j;
+
+ for (j = 1; j < argc; j++) {
+ tmp = getdate(argv[j]);
+
+ if (tmp == NULL) {
+ printf("Call %d failed; getdate_err = %d\en",
+ j, getdate_err);
+ continue;
+ }
+
+ printf("Call %d (\e"%s\e") succeeded:\en", j, argv[j]);
+ printf(" tm_sec = %d\en", tmp\->tm_sec);
+ printf(" tm_min = %d\en", tmp\->tm_min);
+ printf(" tm_hour = %d\en", tmp\->tm_hour);
+ printf(" tm_mday = %d\en", tmp\->tm_mday);
+ printf(" tm_mon = %d\en", tmp\->tm_mon);
+ printf(" tm_year = %d\en", tmp\->tm_year);
+ printf(" tm_wday = %d\en", tmp\->tm_wday);
+ printf(" tm_yday = %d\en", tmp\->tm_yday);
+ printf(" tm_isdst = %d\en", tmp\->tm_isdst);
+ }
+
+ exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR time (2),
.BR localtime (3),
+.BR setlocale (3),
.BR strftime (3),
-.BR strptime (3),
-.BR time (3)
+.BR strptime (3)
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