[ excerpt from commands' man page ]

Port of NetBSD's pgrep(1) and pkill(1) commands which either find
or signal processes matching criteria.

The pgrep command searches the process table on the running system
and prints the process IDs of all processes that match the criteria
given on the command line.

The pkill command searches the process table on the running system
and signals all processes that match the criteria given on the
command line.