Check if a command is running already, if not start it with the provided arguments.

run-once.sh

#!/bin/bash
# Check if a command is running already, if not start it with the provided arguments.
#
# Example:
# This will check if thunar is already running if not it will start it with the --daemon argument.
# ./run-once.sh thunar --daemon
#
# I use it for my awesomewm autostart script which is available here:
# https://github.com/razius/awesomewm/blob/master/autostart.sh

PID=`pgrep -f -x "$1"`
if [[ -z $PID ]]
then
	echo "Starting $@"
	`$@ > /dev/null 2>&1 &`
else
	echo "$1 already running with $PID."
fi