Behaves the same as strftime() except that the
time returned is Greenwich Mean Time (GMT). For example, when run
in Eastern Standard Time (GMT -0500), the first line below prints
"Dec 31 1998 20:00:00", while the second prints "Jan 01 1999
01:00:00".
The optional timestamp
parameter is an
integer Unix timestamp that defaults to the current
local time if a timestamp
is not given. In other
words, it defaults to the value of time().
Return Values
Returns a string formatted according to the given format string
using the given timestamp
or the current
local time if no timestamp is given. Month and weekday names and
other language dependent strings respect the current locale set
with setlocale().