Run bash script as daemon

Question

I have a script, which runs my PHP script each X times:

#!/bin/bash
while true; do
/usr/bin/php -f ./my-script.php
echo "Waiting..."
sleep 3
done

How can I start it as daemon?

Answer 1

To run it as a full daemon from a shell, you'll need to use setsid and redirect its output. You can redirect the output to a logfile, or to /dev/null to discard it. Assuming your script is called myscript.sh, use the following command:

setsid myscript.sh >/dev/null 2>&1 < /dev/null &

This will completely detach the process from your current shell (stdin, stdout and stderr). If you want to keep the output in a logfile, replace the first /dev/null with your /path/to/logfile.

You have to redirect the output, otherwise it will not run as a true daemon (it will depend on your shell to read and write output).