Section: User Commands (1)
Updated: July 2014
renice alters the scheduling priority of one or more running processes. The first argument is the priority value to be used. The other arguments are interpreted as process IDs (by default), process group IDs, user IDs, or user names. renice'ing a process group causes all processes 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.
- -n, --priority priority
- Specify the scheduling priority to be used for the process, process group, or user. Use of the option -n or --priority is optional, but when used it must be the first argument.:
- -g, --pgrp
- Interpret the succeeding arguments as process group IDs.:
- -p, --pid
- Interpret the succeeding arguments as process IDs (the default).:
- -u, --user
- Interpret the succeeding arguments as usernames or UIDs.:
- -h, --help
- Display help text and exit.:
- -V, --version
- Display version information and exit.:
The following command would change the priority of the processes with PIDs 987 and 32, plus all processes owned by the users daemon and root:
:renice +1 987 -u daemon root -p 32
Users other than the superuser may only alter the priority of processes they own, and can only monotonically increase their ``nice value (for security reasons) within the range 0 to 19, unless a nice resource limit is set (Linux 2.6.12 and higher). The superuser may alter the priority of any process and set the priority to any value in the range -20 to 19. 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).
- to map user names to user IDs:
Non-superusers cannot increase scheduling priorities of their own processes, even if they were the ones that decreased the priorities in the first place.
The Linux kernel (at least version 2.0.0) and linux libc (at least version 5.2.18) does not agree entirely on what the specifics of the systemcall interface to set nice values is. Thus causes renice to report bogus previous nice values.
The renice command is part of the util-linux package and is available from Linux Kernel Archive