renice(8)
Name
renice − alter priority of running processes
Syntax
/etc/renice priority [ [ −p ] pid ... ] [ [ −g ] pgrp ... ] [ [ −u ] user ... ]
Description
The renice command alters the scheduling priority of one or more running processes. The who parameters are interpreted as process ID’s, process group ID’s, or user names. Using renice on a process group causes all processes in the process group to have their scheduling priority altered. Using renice on a user causes all processes owned by the user to have their scheduling priority altered. By default, the processes to be affected are specified by their process ID’s.
Options
To force who parameters to be interpreted as process group ID’s, a −g may be specified. To force the who parameters to be interpreted as user names, a −u may be given. Supplying −p will reset who interpretation to be (the default) process ID’s.
Users other than the superuser may only alter the priority of processes they own, and can only monotonically increase their “nice value” within the range 0 to PRIO_MIN (20). (This prevents overriding administrative fiats.) The superuser can alter the priority of any process and set the priority to any value in the range PRIO_MAX (−20) to PRIO_MIN. Useful priorities are: 19 (the affected processes will run only when nothing else in the system wants to), 0 (the “base” scheduling priority), anything negative (to make things go very fast).
Examples
The following command changes the priority of process ID’s 987 and 32, and all processes owned by users daemon and root:
/etc/renice +1 987 −u daemon root −p 32
Restrictions
If you make the priority very negative, then the process cannot be interrupted. To regain control you make the priority greater than zero. Non-superusers cannot increase scheduling priorities of their own processes, even if they were the ones that decreased the priorities in the first place.
Files
/etc/passwd Maps user names to user IDs