Timezone conversion using date

Many users may already use date to check the time from a console, but this week we're going to show you how it can be used to convert timezones. For example, most Gentoo announcements are timestamped in UTC. To convert a time to your timezone, use the following, which uses /etc/localtime to determine the target timezone:

Code Listing 1: Converting to the local timezone

% date -d '17:00 UTC' 
Sun Mar 28 12:00:00 EST 2004

If you want to convert to a different timezone, you can set the TZ enviornment variable to the appropriate timezone. There's a pitfall here: if GNU date doesn't find TZ in /usr/share/zoneinfo, it'll fall back to /etc/localtime without warning or error, so be careful. Here's an example of doing the reverse conversion from the previous example:

Code Listing 2: Converting to UTC

% TZ=UTC date -d '12:00 EST' 
Sun Mar 28 17:00:00 EST 2004

From http://www.gentoo.org/news/en/gwn/20040329-newsletter.xml