mirror of https://github.com/mkerrisk/man-pages
304 lines
7.8 KiB
Groff
304 lines
7.8 KiB
Groff
.\" Copyright 2001 walter harms (walter.harms@informatik.uni-oldenburg.de)
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.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" Modified, 2001-12-26, aeb
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.\" 2008-09-07, mtk, Various rewrites; added an example program.
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.\"
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.TH GETDATE 3 2010-09-20 "" "Linux Programmer's Manual"
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.SH NAME
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getdate, getdate_r \- convert a date-plus-time string to broken-down time
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.SH SYNOPSIS
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.B "#include <time.h>"
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.sp
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.BI "struct tm *getdate(const char *" string );
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.sp
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.B "extern int getdate_err;"
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.sp
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.B "#include <time.h>"
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.sp
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.BI "int getdate_r(const char *" string ", struct tm *" res );
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.BR getdate ():
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.ad l
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.RS 4
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_XOPEN_SOURCE\ >=\ 500 ||
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_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
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.RE
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.br
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.BR getdate_r ():
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.ad l
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.RS 4
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_GNU_SOURCE
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.RE
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.ad
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.SH DESCRIPTION
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The function
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.BR getdate ()
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converts a string representation of a date and time,
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contained in the buffer pointed to by
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.IR string ,
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into a broken-down time.
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The broken-down time is stored in a
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.I tm
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structure, and a pointer to this
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structure is returned as the function result.
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This
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.I tm
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structure is allocated in static storage,
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and consequently it will be overwritten by further calls to
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.BR getdate ().
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In contrast to
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.BR strptime (3),
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(which has a
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.I format
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argument),
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.BR getdate ()
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uses the formats found in the file
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whose full pathname is given in the environment variable
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.BR DATEMSK .
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The first line in the file that matches the given input string
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is used for the conversion.
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The matching is done case insensitively.
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Superfluous whitespace, either in the pattern or in the string to
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be converted, is ignored.
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The conversion specifications that a pattern can contain are those given for
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.BR strptime (3).
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One more conversion specification is specified in POSIX.1-2001:
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.TP
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.B %Z
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Timezone name.
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This is not implemented in glibc.
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.LP
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When
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.B %Z
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is given, the structure containing the broken-down time
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is initialized with values corresponding to the current
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time in the given timezone.
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Otherwise, the structure is initialized to the broken-down time
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corresponding to the current local time (as by a call to
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.BR localtime (3)).
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.LP
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When only the weekday is given, the day is taken to be the first such day
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on or after today.
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.LP
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When only the month is given (and no year), the month is taken to
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be the first such month equal to or after the current month.
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If no day is given, it is the first day of the month.
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.LP
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When no hour, minute and second are given, the current
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hour, minute and second are taken.
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.LP
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If no date is given, but we know the hour, then that hour is taken
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to be the first such hour equal to or after the current hour.
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.BR getdate_r ()
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is a GNU extension that provides a reentrant version of
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.BR getdate ().
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Rather than using a global variable to report errors and a static buffer
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to return the broken down time,
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it returns errors via the function result value,
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and returns the resulting broken-down time in the
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caller-allocated buffer pointed to by the argument
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.IR res .
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.SH "RETURN VALUE"
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When successful,
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.BR getdate ()
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returns a pointer to a
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.IR "struct tm" .
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Otherwise, it returns NULL and sets the global variable
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.IR getdate_err
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to one of the error numbers shown below.
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Changes to
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.I errno
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are unspecified.
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On success
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.BR getdate_r ()
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returns 0;
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on error it returns one of the error numbers shown below.
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.SH ERRORS
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The following errors are returned via
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.IR getdate_err
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(for
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.BR getdate ())
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or as the function result (for
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.BR getdate_r ()):
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.TP 4n
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.B 1
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The
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.B DATEMSK
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environment variable is not defined, or its value is an empty string.
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.TP
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.B 2
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The template file specified by
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.B DATEMSK
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cannot be opened for reading.
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.TP
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.B 3
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Failed to get file status information.
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.\" stat()
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.TP
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.B 4
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The template file is not a regular file.
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.TP
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.B 5
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An error was encountered while reading the template file.
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.TP
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.B 6
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Memory allocation failed (not enough memory available).
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.\" Error 6 doesn't seem to occur in glibc
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.TP
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.B 7
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There is no line in the file that matches the input.
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.TP
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.B 8
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Invalid input specification.
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.SH ENVIRONMENT
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.TP
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.B DATEMSK
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File containing format patterns.
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.TP
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.BR TZ ", " LC_TIME
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Variables used by
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.BR strptime (3).
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.SH "CONFORMING TO"
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POSIX.1-2001.
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.SH NOTES
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The POSIX.1-2001 specification for
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.BR strptime (3)
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contains conversion specifications using the
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.B %E
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or
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.B %O
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modifier, while such specifications are not given for
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.BR getdate ().
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In glibc,
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.BR getdate ()
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is implemented using
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.BR strptime (3),
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so that precisely the same conversions are supported by both.
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.SH EXAMPLE
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The program below calls
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.BR getdate ()
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for each of its command-line arguments,
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and for each call displays the values in the fields of the returned
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.I tm
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structure.
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The following shell session demonstrates the operation of the program:
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.in +4n
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.nf
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.RB "$" " TFILE=$PWD/tfile"
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.RB "$" " echo \(aq%A\(aq > $TFILE " " # Full weekday name"
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.RB "$" " echo \(aq%T\(aq >> $TFILE" " # ISO date (YYYY-MM-DD)"
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.RB "$" " echo \(aq%F\(aq >> $TFILE" " # Time (HH:MM:SS)"
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.RB "$" " date"
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.RB "$" " export DATEMSK=$TFILE"
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.RB "$" " ./a.out Tuesday \(aq2009-12-28\(aq \(aq12:22:33\(aq"
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Sun Sep 7 06:03:36 CEST 2008
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Call 1 ("Tuesday") succeeded:
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tm_sec = 36
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tm_min = 3
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tm_hour = 6
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tm_mday = 9
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tm_mon = 8
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tm_year = 108
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tm_wday = 2
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tm_yday = 252
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tm_isdst = 1
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Call 2 ("2009-12-28") succeeded:
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tm_sec = 36
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tm_min = 3
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tm_hour = 6
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tm_mday = 28
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tm_mon = 11
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tm_year = 109
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tm_wday = 1
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tm_yday = 361
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tm_isdst = 0
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Call 3 ("12:22:33") succeeded:
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tm_sec = 33
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tm_min = 22
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tm_hour = 12
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tm_mday = 7
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tm_mon = 8
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tm_year = 108
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tm_wday = 0
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tm_yday = 250
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tm_isdst = 1
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.fi
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.in
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.SS Program source
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\&
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.nf
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#define _GNU_SOURCE 500
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#include <time.h>
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#include <stdio.h>
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#include <stdlib.h>
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int
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main(int argc, char *argv[])
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{
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struct tm *tmp;
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int j;
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for (j = 1; j < argc; j++) {
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tmp = getdate(argv[j]);
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if (tmp == NULL) {
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printf("Call %d failed; getdate_err = %d\\n",
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j, getdate_err);
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continue;
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}
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printf("Call %d (\\"%s\\") succeeded:\\n", j, argv[j]);
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printf(" tm_sec = %d\\n", tmp\->tm_sec);
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printf(" tm_min = %d\\n", tmp\->tm_min);
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printf(" tm_hour = %d\\n", tmp\->tm_hour);
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printf(" tm_mday = %d\\n", tmp\->tm_mday);
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printf(" tm_mon = %d\\n", tmp\->tm_mon);
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printf(" tm_year = %d\\n", tmp\->tm_year);
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printf(" tm_wday = %d\\n", tmp\->tm_wday);
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printf(" tm_yday = %d\\n", tmp\->tm_yday);
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printf(" tm_isdst = %d\\n", tmp\->tm_isdst);
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}
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exit(EXIT_SUCCESS);
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}
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.fi
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.SH "SEE ALSO"
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.BR time (2),
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.BR localtime (3),
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.BR setlocale (3),
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.BR strftime (3),
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.BR strptime (3)
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