getdate(3C) getdate(3C)
NAME
getdate - convert date and time
SYNOPSIS
#include <time.h>
struct tm *getdate(const char *string);
extern int getdateerr;
DESCRIPTION
getdate() converts user-definable date and/or time specifications
pointed to by string into a tm structure. The structure declaration is
in the time.h header file [see also ctime(3C)].
User-supplied templates are used to parse and interpret the input
string. The templates are text files created by the user and identi-
fied via the environment variable DATEMSK. Each line in the template
represents an acceptable date and/or time specification using some of
the same field descriptors as the ones used by the date command. The
first line in the template that matches the input specification is
used for interpretation and conversion into the internal time format.
If successful, the function getdate() returns a pointer to a tm struc-
ture; otherwise, it returns NULL and sets the global variable
getdateerr to indicate the error.
The following field descriptors are supported:
%% same as %
%a abbreviated weekday name
%A full weekday name
%b abbreviated month name
%B full month name
%c locale's appropriate date and time representation
%d day of month (01 - 31; the leading 0 is optional)
%e same as %d
%D date as %m/%d/%y
%h abbreviated month name
%H hour (00 - 23)
%I hour (01 - 12)
%m month number (01 - 12)
%M minute (00 - 59)
%n same as \n
%p locale's equivalent of either AM or PM
%r time as %I:%M:%S %p
%R time as %H:%M
%S seconds (00 - 59)
%t insert a tab
%T time as %H:%M:%S
%w weekday number (0 - 6; Sunday = 0)
%x locale's appropriate date representation
%X locale's appropriate time representation
%y year with century (00 - 99)
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getdate(3C) getdate(3C)
%Y year as ccyy (e.g., 1986)
%Z time zone name or no characters if no time zone exists.
If the time zone supplied by %Z is not the time zone that get-
date() expects, an invalid input specification error will result.
The getdate() function calculates an expected time zone based on
information supplied to the function (such as the hour, day, and
month).
The match between the template and input specification performed by
getdate() is case insensitive.
The month and weekday names can consist of any combination of upper
and lower case letters. The user can request that the input date or
time specification be in a specific language by setting the categories
LCTIME and LCCTYPE of setlocale().
Leading 0's are not necessary for the descriptors that allow leading
0's. However, at most two digits are allowed for those descriptors,
including leading 0's. Extra white-space in either the template file
or in string is ignored.
The field descriptors %c, %x, and %X will not be supported if they
include unsupported field descriptors.
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getdate(3C) getdate(3C)
The following rules are applied for converting the input specification
into the internal format:
- If %Z is being scanned, then getdate() initializes the broken-down
time to be the current time in the scanned time zone. Otherwise it
initializes the broken-down time based on the current local time as
if localtime() had been called.
- If only the weekday is given, today is assumed if the given day is
equal to the current day and next week if it is less.
- If only the month is given, the current month is assumed if the
given month is equal to the current month and next year if it is
less and no year is given. (The first day of month is assumed if no
day is given.)
- If no hour, minute, and second are given, the current hour, minute,
and second are assumed.
- If no date is given, today is assumed if the given hour is greater
than the current hour and tomorrow is assumed if it is less.
RESULT
On failure getdate() returns NULL and sets the variable getdateerr()
to indicate the error.
The meanings of the possible values of getdateerr() are as follows:
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 was encountered while reading the template file.
6 malloc() could not be executed successfully because not enough
memory was available.
7 There is no line in the template that matches the input.
8 The input specification is invalid (e.g., February 31).
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getdate(3C) getdate(3C)
EXAMPLES
Example 1:
The following example shows the possible contents of a template:
%m
%A %B %d %Y, %H:%M:%S
%A
%B
%m/%d/%y %I %p
%d,%m,%Y %H:%M
at %A the %dst of %B in %Y
run job at %I %p,%B %dnd
%A the %d. %B %Y %H.%M o'clock
Example 2:
The following are examples of valid input specifications for the above
template:
getdate("10/1/87 4 PM")
getdate("Friday")
getdate("Friday September 19 1987, 10:30:30")
getdate("24,9,1986 10:30")
getdate("at Monday the 1st of December in 1986")
getdate("run job at 3 PM, December %2nd")
If the LANG environment variable is set to German, the following is
valid:
getdate("Freitag den 10. Oktober 1986 10.30 Uhr")
Example 3:
Local time and date specification are also supported. The following
examples show how local date and time specification can be defined in
the template.
Invocation | Line in Template
__________________________|__________________
getdate("11/27/86") | %m/%d/%y
getdate("27.11.86") | %d.%m.%y
getdate("86-11-27") | %y-%m-%d
getdate("Friday 12:00:00")| %A %H:%M:%S
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getdate(3C) getdate(3C)
Example 4:
The following examples illustrate the above rules. Assume that the
current date is Mon Sep 22 12:19:47 EDT 1986 and the LANG environment
variable is not set.
| Line in |
Input | Template | Date
____________|___________|______________________________
Mon | %a | Mon Sep 22 12:19:48 EDT 1986
Sun | %a | Sun Sep 28 12:19:49 EDT 1986
Fri | %a | Fri Sep 26 12:19:49 EDT 1986
September | %B | Mon Sep 1:19:49 EDT 1986
January | %B | Thu Jan 1:19:49 EST 1987
December | %B | Mon Dec 1:19:49 EST 1986
Sep Mon | %b %a | Mon Sep 1:19:50 EDT 1986
Jan Fri | %b %a | Fri Jan 2 12:19:50 EST 1987
Dec Mon | %b %a | Mon Dec 1:19:50 EST 1986
Jan Wed 1989| %b %a %Y | Wed Jan 4 12:19:51 EST 1989
Fri 9 | %a %H | Fri Sep 26 09:00:00 EDT 1986
Feb 10:30 | %b %H:%S | Sun Feb 1 10:00:30 EST 1987
10:30 | %H:%M | Tue Sep 23 10:30:00 EDT 1986
13:30 | %H:%M | Mon Sep 22 13:30:00 EDT 1986
NOTES
Subsequent calls to getdate() alter the contents of getdateerr.
Dates before 1970 and after 2037 are illegal.
getdate() makes explicit use of macros described in ctype(3C).
FILES
/usr/lib/locale/locale/LCTIME
language specific printable files
/usr/lib/locale/locale/LCCTYPE
code set specific printable files
SEE ALSO
ctime(3C), ctype(3C), localtime(3C), setlocale(3C), strftime(3C),
environ(5), time(5).
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