CTIME(2) CTIME(2)
NAME
ctime, localtime, gmtime, asctime, tm2sec, timezone -
convert date and time
SYNOPSIS
#include <u.h>
#include <libc.h>
char* ctime(long clock)
Tm* localtime(long clock)
Tm* gmtime(long clock)
char* asctime(Tm *tm)
long tm2sec(Tm *tm)
/env/timezone
DESCRIPTION
Ctime converts a time clock such as returned by time(2) into
ASCII (sic) and returns a pointer to a 30-byte string in the
following form. All the fields have constant width.
Wed Aug 5 01:07:47 EST 1973\n\0
Localtime and gmtime return pointers to structures contain-
ing the broken-down time. Localtime corrects for the time
zone and possible daylight savings time; gmtime converts
directly to GMT. Asctime converts a broken-down time to
ASCII and returns a pointer to a 30-byte string.
typedef
struct {
int sec; /* seconds (range 0..59) */
int min; /* minutes (0..59) */
int hour; /* hours (0..23) */
int mday; /* day of the month (1..31) */
int mon; /* month of the year (0..11) */
int year; /* year A.D. - 1900 */
int wday; /* day of week (0..6, Sunday = 0) */
int yday; /* day of year (0..365) */
char zone[4]; /* time zone name */
int tzoff; /* time zone delta from GMT */
} Tm;
Tm2sec converts a broken-down time to seconds since the
start of the epoch. It ignores wday, and assumes the local
time zone if zone is not GMT.
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CTIME(2) CTIME(2)
When local time is first requested, the program consults the
timezone environment variable to determine the time zone and
converts accordingly. (This variable is set at system boot
time by init(8).) The timezone variable contains the normal
time zone name and its difference from GMT in seconds fol-
lowed by an alternate (daylight) time zone name and its dif-
ference followed by a newline. The remainder is a list of
pairs of times (seconds past the start of 1970, in the first
time zone) when the alternate time zone applies. For exam-
ple:
EST -18000 EDT -14400
9943200 25664400 41392800 57718800 ...
Greenwich Mean Time is represented by
GMT 0 GMT 0
0
SOURCE
/sys/src/libc/9sys
SEE ALSO
date(1), time(2), init(8)
BUGS
The return values point to static data whose content is
overwritten by each call.
Daylight Savings Time is ``normal'' in the Southern hemi-
sphere.
These routines are not equipped to handle non-ASCII text,
and are provincial anyway.
These routines may garble the date when passed a date parsed
with tmparse(2).
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