Linux date manipulation
The date command in Linux is very powerful for converting dates and times. If you have a given time in another timezone, or even UTC, you can convert it to your local timezone with this command:
date -d '2008-05-13 14:00 UTC'
If you want to convert a given time into unixtime just use a date format:
date +%s -d '2008-05-13 14:00 UTC'