This system environment variable determines which time zone is used when formatting a time. As such, it controls the conversion from an internal time base to the appropriate local time. The syntax is TZ=NNNshh:mmDDD, where:
NNN is the time zone name.
s is an optional sign.
hh and mm are the offset in hours and minutes from GMT. Positive offsets represent time zones behind GMT, negative offsets represent those ahead of GMT.
DDD is the corresponding name of Daylight Savings time when it is in effect.
For example, in the eastern United States, TZ is set to EST5EDT - eastern standard time/eastern daylight time, where EST is five hours behind GMT.
All UNIX systems use a system initialization file to set this variable.