renice
alter priority of running processes
Synopsis
renice [-n]
priority [
[-p] pid ... ] [
[-g] pgrp ... ] [
[-u] user ... ]
renice -h |
-v
add an example, a script, a trick and tips
examples
source
files="$*"
renice -20 $$
tail -n 0 -f $files
source
zhone > /tmp/zhone.log 2>&1 &
renice -3 $!
source
ophonekitd >> /var/log/ophonekitd.log 2>&1 &
renice -3 $!
description
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 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.
By default, the processes to be affected are specified by
their process ID’s.
Options
supported by renice:
-n,
--priority
The scheduling priority
of the process, process group, or user.
-g,
--pgrp
Force who parameters to
be interpreted as process group ID’s.
-u,
--user
Force the who parameters
to be interpreted as user names.
-p,
--pid
Resets the who
interpretation to be (the default) process ID’s.
-v,
--version
Print version.
-h,
--help
Print help.
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’’ (for security
reasons) within the range 0 to PRIO_MAX (20), unless a nice
resource limit is set (Linux 2.6.12 and higher). 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),
anything negative (to make things go very fast).
availability
The renice command is part of the util-linux package and is
available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
util-linux November 2010 util-linux
g-
--pgrp
Force who parameters to be interpreted as process group
ID’s.
h-
--help
Print help.
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’’ (for security reasons) within the range 0 to
PRIO_MAX (20), unless a nice resource limit is set (Linux 2.6.12
and higher). 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), anything negative (to make things
go very fast).
p-
--pid
Resets the who interpretation to be (the default) process
ID’s.
u-
--user
Force the who parameters to be interpreted as user names.
v-
--version
Print version.
bugs
Non super-users can not 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.
history
The renice command
appeared in 4.0BSD.
see also
/etc/passwd
to map user
names to user ID’s
getpriority,
setpriority