linux - renice (8)

     renice - alter priority of running processes

     renice priority [[-p] pid ...] [[-g] pgrp ...] [[-u] user ...]

     Renice alters the scheduling priority of one or more running processes.
     The following who parameters are interpreted as process ID's, process
     group ID's, or user names.  Renice'ing a process group causes all pro-
     cesses in the process group to have their scheduling priority altered.
     Renice'ing 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 supported by renice:

     -g      Force who parameters to be interpreted as process group ID's.

     -u      Force the who parameters to be interpreted as user names.

     -p      Resets the who interpretation to be (the default) process ID's.

     For example,

     renice +1 987 -u daemon root -p 32

     would change the priority of process ID's 987 and 32, and all processes
     owned by users daemon and root.

     Users other than the super-user may only alter the priority of processes
     they own, and can only monotonically increase their ``nice value'' within
     the range 0 to PRIO_MAX (20).  (This prevents overriding administrative
     fiats.)  The super-user may alter the priority of any process and set the
     priority to any value in the range PRIO_MIN (-20) to PRIO_MAX. Useful
     priorities are: 20 (the affected processes will run only when nothing
     else in the system wants to), 0 (the ``base'' scheduling priority), any-
     thing negative (to make things go very fast).

     /etc/passwd  to map user names to user ID's

     getpriority(2),  setpriority(2)

     Non super-users can not increase scheduling priorities of their own pro-
     cesses, even if they were the ones that decreased the priorities in the
     first place.

     The renice command appeared in 4.0BSD.