What is the difference between the two commands
renice to manage process priority?
nice launches a new command with a modified nice level (lower priority than it would have otherwise had, or higher priority if you have permission). You specify which command to launch by providing it as an argument to
execs that command, so
nice itself doesn't terminate until the command does.
renice changes the priority of an existing running process, then terminates immediately. You specify which process by giving its PID (as well as the new desired nice level) as an argument to
Note also that
nice takes a relative nice level (i.e. less or more than before) whereas
renice requires an absolute level.