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linuxbashservicepid

Get PID of backround process lauched as other users

I'm trying to store the PID of a background process I need to launch as a non-root user.

When I execute the script below, the PID file is created but stays empty. 

USER=myuser
PROG=/path/to/service
PROG_ARGS=""
PIDFILE=/var/run/$NAME.pid 

su $USER -c "python2.7 $PROG $PROG_ARGS &"    
echo $! > $PIDFILE

I've tried to place the & outside the su command like so su $USER -c "python ..." &, and it nearly worked since I get a PID but it's always the one before my actual process (Eg: if my python PID is 3101, the saved PID will be 3100). I suspect this is the PID of the shell that launched the python script.

My question is, how can I launch my python script as a specific user and save the PID at the same time?

I'm running RHLE 6.

Solution

  • The background process is created in the subshell started by su, so you need to capture $! there.

    su $USER -c "python2.7 $PROG $PROG_ARGS & echo \$! > $PID_FILE"