How to run a command as a specific user in an init script?

Question

I'm writing an init script which is supposed to execute a single command as a user different than root. This is how I'm doing it currently:
sudo -u username command

This generally works as expected on Ubuntu/Debian, but on RHEL the script which is executed as the command hangs.
Is there another way to run the command as another user?
(Note that I can't use lsb init functions as they're not available on RHEL/Centos 5.x.)

Answer 1

On RHEL systems, the /etc/rc.d/init.d/functions script is intended to provide similar to what you want. If you source that at the top of your init script, all of it's functions become available.

The specific function provided to help with this is daemon. If you are intending to use it to start a daemon-like program, a simple usage would be:

daemon --user=username command 

If that is too heavy-handed for what you need, there is runuser (see man runuser for full info; some versions may need -u prior to the username):

/sbin/runuser username -s /bin/bash -c "command(s) to run as user username" 

Answer 2

For systemd style init scripts it's really easy. You just add a User= in the [Service] section.

Here is an init script I use for qbittorrent-nox on CentOS 7:

[Unit] Description=qbittorrent torrent server  [Service] User=<username> ExecStart=/usr/bin/qbittorrent-nox Restart=on-abort  [Install] WantedBy=multi-user.target