find the process ID of a running program.
pidof [-s] [-c] [-x] [-m] [-o omitpid] [-o omitpid..] program [program..]
Pidof finds the process idâ€™s (pids) of the named programs. It prints
those idâ€™s on the standard output. This program is on some systems used
in run-level change scripts, especially when the system has a System-V
like rc structure. In that case these scripts are located in
/etc/rc?.d, where ? is the runlevel. If the system has a start-stop-
daemon (8) program that should be used instead.