Format
TZ= standardHH[:MM[:SS]]
[daylight[HH[:MM[:SS:]]] [,startdate[/starttime],enddate[/endtime]]
]
Description
All commands assume that times
stored in the file system and returned by the operating system are
stored using Universal Time Coordinated (UTC),
hereafter referred to as the universal reference time. The mapping
from the universal reference time to local time is specified by the
TZ (time zone) environment variable.
The value of the TZ environment
variable has these fields (two required and three optional):
- standard
- An alphabetic abbreviation for the local standard time zone; for
example, GMT, EST, MSEZ.
- HH[:MM[:SS]]
- The time offset westward from the universal reference time. A
leading minus sign (-) means that the local time zone is east of the
universal reference time. An offset of this form must follow standard and
can also optionally follow daylight. An
optional colon (:) separates hours from optional minutes and seconds.
If daylight is specified without a daylight offset,
daylight saving time is assumed to be one hour ahead of the standard
time.
- [daylight]
- The abbreviation for your local daylight saving time zone. If
the daylight field is missing, the conversion to daylight saving time
is disabled. The number of hours, minutes, and seconds your local
daylight saving time is offset from UTC when daylight saving time
is in effect. If the daylight saving time abbreviation is specified,
and the offset omitted, the offset of one hour is assumed.
- [,startdate[/starttime],enddate[/endtime]]
- A rule that identifies the start and end of daylight saving time,
specifying when it should be in effect. Both the startdate and enddate must
be present, and must either take the form Jn, n,
or Mm.w.d..
- Jn is the Julian day n (1 <= n <=365).
Leap days are not counted. In all years, including leap years, February
28 is day 59 and March 9 is day 60. It is impossible to implicitly
refer to the occasional February 29.
- n is the zero-based Julian day (0 <= n <=
365). Leap days are counted, and it is possible to refer to February
29.
- Non-leap year
- January 1
- Day 0
- February 28
- Day 58
- March 1
- Day 59
- December 31
- Day 364
- Leap year
- January 1
- Day 0
- February 29
- Day 59
- March 1
- Day 60
- December 31
- Day 365
- Mm.w.d defines the
day (0 <= d <= 6) of week w (1 <= w <=
5) of month m (1 <= 12) of the year.
Week 5 has the last day (d) in month m,
which may occur in either the fourth or fifth week). Week 1 is the
first week in which the dth day occurs.
Day zero is Sunday.
Neither starttime nor endtime are
required. If they are omitted, their values default to 02:00:00. If
this daylight saving time rule is omitted altogether, the values in
the rule default to the standard rules for American daylight saving
time.
When the TZ variable is not
set, time conversions behave as if TZ were set to TZ=GMT0.
Portability
This interpretation of the
TZ environment variable is a superset of that supported by UNIX System V.
Description
The locale, date and touch commands.