pidof [-s] [-x] [-o omitpid..] program [program..]
Return the process ID of a process which is running the program named on the command line.
instructs the program to only return one pid.
causes the program to also return process id's of shells running the named scripts.
omits processes with specified process id.
Need further investigation on the behavior of various implementations concerning whether program is a full pathname, the basename only, the program as named by argv, or what.