Set system time zone in Linux

Question

Are there any functions in C language to set system time in Linux? I have to set my system time zone also. I other words, if my timezone is IST, can I set it to UTC?

Answer 1

Use stime to set the time,and tzset to set the timezone.

Note that the tz (timezone) parameter to settimeofday is obsolete.

Answer 2

The default time zone, used by processes that don't have a TZ variable in their environment, is decided by the contents of /etc/localtime. Find the time zone you want in /usr/share/zoneinfo and copy or symlink it.

rm /etc/localtime
ln -s /usr/share/zoneinfo/Etc/GMT /etc/localtime

There are some interactive tools to help you pick a time zone, but they vary by distribution (e.g. Debian's dpkg-reconfigure tzdata)