Bash init - start service under specific user

Question

I am trying to create an init script in bash (Ubuntu) that starts a service under a specific user.

Is there a better way to do that other than this?

su - <user>  -c "bash -c  'cd $DIR ;<service name>'"

Answer 1

Ubuntu uses start-stop-daemon which already supports this feature.

Use the skeleton file from /etc/init.d:

sudo cp /etc/init.d/skeleton /etc/init.d/mynewservice

Edit mynewservice appropriately.

Add the following parameter to the lines that call start-stop-daemon:

--chuid username:group

Example:

Change

start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON --test > /dev/null \

to

start-stop-daemon --start --quiet --chuid someuser:somegroup --pidfile $PIDFILE --exec $DAEMON --test > /dev/null \

Finally, register your service and start it:

update-rc.d mynewservice defaults 99 && service mynewservice start

More info about other options for start-stop-daemon here

Answer 2

Alternatively, you can use the daemon function defined in your /etc/init.d/functions file:

daemon --user=<user> $DIR/program

If you look into its syntax you can do other things like defining PID file location, setting nice level, and whatnot. It's otherwise really useful for starting up services as daemons. Services started up with daemon can easily be terminated by another functions function, killproc.