1GETDATE(3)                 Linux Programmer's Manual                GETDATE(3)
2
3
4

NAME

6       getdate,  getdate_r  -  convert  a date-plus-time string to broken-down
7       time
8

SYNOPSIS

10       #include <time.h>
11
12       struct tm *getdate(const char *string);
13
14       extern int getdate_err;
15
16       #include <time.h>
17
18       int getdate_r(const char *string, struct tm *res);
19
20   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
21
22       getdate():
23           _XOPEN_SOURCE >= 500
24       getdate_r():
25           _GNU_SOURCE
26

DESCRIPTION

28       The function getdate() converts a string representation of a  date  and
29       time,  contained in the buffer pointed to by string, into a broken-down
30       time.  The broken-down time is stored in a tm structure, and a  pointer
31       to  this  structure is returned as the function result.  This tm struc‐
32       ture is allocated in static storage, and consequently it will be  over‐
33       written by further calls to getdate().
34
35       In  contrast  to  strptime(3), (which has a format argument), getdate()
36       uses the formats found in the file whose full pathname is given in  the
37       environment  variable DATEMSK.  The first line in the file that matches
38       the given input string is used for the conversion.
39
40       The matching is done case insensitively.  Superfluous  whitespace,  ei‐
41       ther in the pattern or in the string to be converted, is ignored.
42
43       The  conversion  specifications  that  a  pattern can contain are those
44       given for strptime(3).  One more conversion specification is  specified
45       in POSIX.1-2001:
46
47       %Z     Timezone name.  This is not implemented in glibc.
48
49       When %Z is given, the structure containing the broken-down time is ini‐
50       tialized with values corresponding to the current  time  in  the  given
51       timezone.   Otherwise,  the structure is initialized to the broken-down
52       time corresponding to the current local time (as by a  call  to  local‐
53       time(3)).
54
55       When  only  the  day  of  the week is given, the day is taken to be the
56       first such day on or after today.
57
58       When only the month is given (and no year), the month is  taken  to  be
59       the first such month equal to or after the current month.  If no day is
60       given, it is the first day of the month.
61
62       When no hour, minute and second are given, the current hour, minute and
63       second are taken.
64
65       If  no  date is given, but we know the hour, then that hour is taken to
66       be the first such hour equal to or after the current hour.
67
68       getdate_r() is a GNU extension that provides  a  reentrant  version  of
69       getdate().   Rather than using a global variable to report errors and a
70       static buffer to return the broken down time, it returns errors via the
71       function  result  value,  and returns the resulting broken-down time in
72       the caller-allocated buffer pointed to by the argument res.
73

RETURN VALUE

75       When successful, getdate() returns a pointer to a  struct  tm.   Other‐
76       wise,  it  returns NULL and sets the global variable getdate_err to one
77       of the error numbers shown below.  Changes to errno are unspecified.
78
79       On success getdate_r() returns 0; on error it returns one of the  error
80       numbers shown below.
81

ERRORS

83       The following errors are returned via getdate_err (for getdate()) or as
84       the function result (for getdate_r()):
85
86       1   The DATEMSK environment variable is not defined, or its value is an
87           empty string.
88
89       2   The  template  file specified by DATEMSK cannot be opened for read‐
90           ing.
91
92       3   Failed to get file status information.
93
94       4   The template file is not a regular file.
95
96       5   An error was encountered while reading the template file.
97
98       6   Memory allocation failed (not enough memory available).
99
100       7   There is no line in the file that matches the input.
101
102       8   Invalid input specification.
103

ENVIRONMENT

105       DATEMSK
106              File containing format patterns.
107
108       TZ, LC_TIME
109              Variables used by strptime(3).
110

ATTRIBUTES

112       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
113       tributes(7).
114
115       ┌────────────┬───────────────┬───────────────────────────────────┐
116Interface   Attribute     Value                             
117       ├────────────┼───────────────┼───────────────────────────────────┤
118getdate()   │ Thread safety │ MT-Unsafe race:getdate env locale │
119       ├────────────┼───────────────┼───────────────────────────────────┤
120getdate_r() │ Thread safety │ MT-Safe env locale                │
121       └────────────┴───────────────┴───────────────────────────────────┘

CONFORMING TO

123       POSIX.1-2001, POSIX.1-2008.
124

NOTES

126       The  POSIX.1 specification for strptime(3) contains conversion specifi‐
127       cations using the %E or %O modifier, while such specifications are  not
128       given  for  getdate().   In glibc, getdate() is implemented using strp‐
129       time(3), so that precisely the same conversions are supported by both.
130

EXAMPLES

132       The program below calls getdate() for each of  its  command-line  argu‐
133       ments,  and  for each call displays the values in the fields of the re‐
134       turned tm structure.  The following shell session demonstrates the  op‐
135       eration of the program:
136
137           $ TFILE=$PWD/tfile
138           $ echo '%A' > $TFILE       # Full name of the day of the week
139           $ echo '%T' >> $TFILE      # ISO date (YYYY-MM-DD)
140           $ echo '%F' >> $TFILE      # Time (HH:MM:SS)
141           $ date
142           $ export DATEMSK=$TFILE
143           $ ./a.out Tuesday '2009-12-28' '12:22:33'
144           Sun Sep  7 06:03:36 CEST 2008
145           Call 1 ("Tuesday") succeeded:
146               tm_sec   = 36
147               tm_min   = 3
148               tm_hour  = 6
149               tm_mday  = 9
150               tm_mon   = 8
151               tm_year  = 108
152               tm_wday  = 2
153               tm_yday  = 252
154               tm_isdst = 1
155           Call 2 ("2009-12-28") succeeded:
156               tm_sec   = 36
157               tm_min   = 3
158               tm_hour  = 6
159               tm_mday  = 28
160               tm_mon   = 11
161               tm_year  = 109
162               tm_wday  = 1
163               tm_yday  = 361
164               tm_isdst = 0
165           Call 3 ("12:22:33") succeeded:
166               tm_sec   = 33
167               tm_min   = 22
168               tm_hour  = 12
169               tm_mday  = 7
170               tm_mon   = 8
171               tm_year  = 108
172               tm_wday  = 0
173               tm_yday  = 250
174               tm_isdst = 1
175
176   Program source
177
178       #define _GNU_SOURCE
179       #include <time.h>
180       #include <stdio.h>
181       #include <stdlib.h>
182
183       int
184       main(int argc, char *argv[])
185       {
186           struct tm *tmp;
187
188           for (int j = 1; j < argc; j++) {
189               tmp = getdate(argv[j]);
190
191               if (tmp == NULL) {
192                   printf("Call %d failed; getdate_err = %d\n",
193                          j, getdate_err);
194                   continue;
195               }
196
197               printf("Call %d (\"%s\") succeeded:\n", j, argv[j]);
198               printf("    tm_sec   = %d\n", tmp->tm_sec);
199               printf("    tm_min   = %d\n", tmp->tm_min);
200               printf("    tm_hour  = %d\n", tmp->tm_hour);
201               printf("    tm_mday  = %d\n", tmp->tm_mday);
202               printf("    tm_mon   = %d\n", tmp->tm_mon);
203               printf("    tm_year  = %d\n", tmp->tm_year);
204               printf("    tm_wday  = %d\n", tmp->tm_wday);
205               printf("    tm_yday  = %d\n", tmp->tm_yday);
206               printf("    tm_isdst = %d\n", tmp->tm_isdst);
207           }
208
209           exit(EXIT_SUCCESS);
210       }
211

SEE ALSO

213       time(2), localtime(3), setlocale(3), strftime(3), strptime(3)
214

COLOPHON

216       This  page  is  part of release 5.10 of the Linux man-pages project.  A
217       description of the project, information about reporting bugs,  and  the
218       latest     version     of     this    page,    can    be    found    at
219       https://www.kernel.org/doc/man-pages/.
220
221
222
223                                  2020-11-01                        GETDATE(3)
Impressum