.TH TZ 5.SH NAMETZ \- Time zone environment variable.SH SYNOPSIS\fBTZ=\fIzone\fR[\fB\-\fR]\fIoffset\fR[\fIdst\fR[\fIoffset\fR][\fB,\fIstart\fR[\fB/\fItime\fR]\fB,\fIend\fR[\fB/\fItime\fR]]].SH DESCRIPTION.de SP.if t .sp 0.4.if n .sp..The.B TZenvironment variable tells functions such as the.BR ctime (3)family and programs like.B datewhat the time zone and daylight saving rule is.  The value of.B TZhas the \s-2POSIX\s+2 standardized form shown in the synopsis.  This formspecifies the zone names, offsets from GMT, and daylight savings changeovertimes for at least the current year..TP.I zoneA three or more letter name for the time zone in normal (winter) time..TP.BI [\-] offsetA signed time telling the offset of the time zone westwards from Greenwich.The time has the form.I hh[:mm[:ss]]with a one of two digit hour, and optional two digit minutes and seconds..TP.I dstThe name of the time zone when daylight savings is in effect.  It maybe followed by an offset telling how big the clock correction is other thanthe default of 1 hour..TP\fIstart\fR/\fItime\fR,\fIend\fR/\fItime\fRSpecifies the start and end of the daylight savings period.  The.I startand.I endfields indicate on what day the changeover occurs.  They must be in one ofthe following formats:.SP.ta +5.in +5.ti -5\fBJ\fIn\fR	The Julian day.I n(1 <=.I n<= 365) ignoring leap days, i.e. there is no February 29..SP.ti -5\fIn\fR	The zero-based Julian day(0 <=.I n<= 365).  Leap days are not ignored..SP.ti -5.BI M m . n . d.brThis indicates month.IR m ,the.IR n -thoccurrence of day.I d(1 <=.I m<= 12, 1 <=.I n<= 5, 0 <=.I d<= 6, 0=Sunday).  The 5-th occurrence means the last occurrence of that dayin a month.  So.B M4.1.0is the first Sunday in April,.B M9.5.0is the last Sunday in September..in -5.SPThe.I timefield indicates the time the changeover occurs on the given day..SH EXAMPLESGreenwich Mean Time:.PP.RS.B TZ=GMT0.RE.PPMiddle European Time, 1 hour east from Greenwich, daylight savings starts onthe last Sunday in March at 2 AM and ends on the last Sunday in Octoberat 3 AM:.PP.RS.B TZ='MET\-1MET DST,M3.5.0/2,M10.5.0/3'.RE.PPBritish time, daylight savings starts and ends at the same moment as MET,but in an earlier time zone:.PP.RS.B TZ=GMT0BST,M3.5.0/1,M10.5.0/2.RE.PPThe eastern european time zones also have the changeovers at the sameabsolute time as British time and MET..PPU.S. Eastern Standard Time, 5 hours west from Greenwich, daylight savingsstarts on the first Sunday in April at 2 AM and ends on the last Sunday inOctober at 2 AM:.PP.RS.B TZ=EST5EDT,M4.1.0/2,M10.5.0/2.RE.PPIt shouldn't surprise you that daylight savings in New Zealand is observedin the months opposite from the previous examples.  It starts on the firstSunday in October at 2 AM and ends on the third Sunday in March at 3 AM:.PP.RS.B TZ=NZST\-12NZDT,M10.1.0/2,M3.3.0/3.RE.SH "SEE ALSO".BR readclock (8),.BR date (1)..SH BUGSYou may have noticed that many fields are optional.  Do no omit them,because the defaults are bogus.  If you need daylight savings then fullyspecify the changeovers..PPWest is negative, east is positive, ask any sailor..SH AUTHORKees J. Bot (kjb@cs.vu.nl)