geeks|programmers — How to convert from/to epoch dates

If you use a Unix system(BSD,Linux,etc.), sometimes you’ll have log files that don’t create the timestamp in regular format such as Apr. 25, 2011 1:10pm but instead it saves the date as the number of seconds since midnight of January 1, 1970 (the date chosen after the fact for the beginning of the Unix epoch).

How to convert from epoch seconds to regular date?

If you’re on any of the BSD systems (such as Mac OS X or FreeBSD), run “date -r SECONDS” from a Terminal:

$ date -r 1302972510

Sat Apr 16 10:48:30 MDT 2011

If you’re using Linux, run “date -d @SECONDS” from a terminal — here’s an example:

$ date -d @1302972510

Sat Apr 16 10:48:30 MDT 2011

Convert from regular date to seconds?

On Linux, here’s an example:

$ date -d “Apr 25, 2011 12:12:12″ +%s

1303755132

For the BSD’s/OS X, here’s an example:

$ date -j -f ‘%Y-%m-%d %H:%M:%S’ ’2011-04-25 12:12:12′ +%s

1303755132

(I’ve had to look this up enough times over the years that I thought i’d finally publish it!