If you are working with Unix a lot, you get to be aware of weird time-stamps. That markup is usually called Unix time (although POSIX time is more precise term) and it represents number of seconds from January 1st 1970 (in UTC).
I was handling some timing issues in log and I needed to convert between local and Unix time. Since I got quite annoyed during day, at night I created small utility to handle this simple task.
Both application and full code is available.