Will "kill -SIGTERM" stop "tail -f"?

Question

Just as the title says, Google gives me nothing and I can't test it on this server.

The command as is follows:

tail -f <file> | fgrep --line-buffered "string" | sed -u 's/stuff//g' >> output.log

Do I need to use kill -SIGTERM <PID> or kill -SIGKILL <PID> to stop a tail -f?

Answer 1

• SIGTERM sends a signal to the command and will tell the command to stop itself. If there is a need to clean-up files due to the kill the command can do that.
• SIGKILL sends a signal to the init system. The command itself does not get even told it is going to get killed.

So you can use both; but SIGTERM should be preferred (it is more graceful).

Will “kill -SIGTERM” stop “tail -f”?

Yes, it will. On Linux tail acts on SIGTERM.

Answer 2

You don't even have to use SIGTERM. tail listens for SIGINT and SIGQUIT too. I'm not sure if there's any difference between signals (it's all specific to tail) but any of these would be better than SIGKILL.

It's quite easy to test too:

$ tail -f /dev/null > /dev/null &
[1] 26599
$ kill -SIGINT $!
[1]+  Interrupt               tail -f /dev/null > /dev/null