Tail

The tail program is a tool used to view the last few lines of a file.

For a cool graphical version, see root-tail.

Examples
It's frequently useful to see only the last 20 or so lines of a log file (which would have the most recent 20 entries), for example if there's something that just went wrong with my computer.

$ tail -20 /var/log/messages
 * See only the last 20 lines of the file /var/log/messages

$ tail -f /var/log/messages
 * To continously monitor the file /var/log/messages

Provided by
Most (all?) Linux distributions incorporate this from the GNU Coreutils: and use its man page