tail stops working

Question

I am tailing a file in unix. It stops working sometimes and I have to re-run the command. Anyone know why this happens?

Answer 1

The tail command stops "working" when it reaches the end of the file unless you ask it to follow the file.

The standard "-f" option allows you to follow a file while it grows but if the file is renamed or removed, tail will stick to the file descriptor so updates won't appear unless the process(es) writing to the file have kept it open.

Depending on the tail implementation, you might also have a '-F' option available which will monitor the file by name so won't be confused by the previously mentioned issue.

Answer 2

It is possible the file is being turned over due to file size, log files do this a lot. So try to use the -f flag so it follows the file.

Usage: tail -F security.log