renice.8

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.\"     @(#)renice.8	8.1 (Berkeley) 6/9/93
.\"
.Dd June 9, 1993
.Dt RENICE 8
.Os BSD 4
.Sh NAME
.Nm renice
.Nd alter priority of running processes
.Sh SYNOPSIS
.Nm renice
.Ar priority
.Oo
.Op Fl p
.Ar pid ...
.Oc
.Oo
.Op Fl g
.Ar pgrp ...
.Oc
.Oo
.Op Fl u
.Ar user ...
.Oc
.Sh DESCRIPTION
.Nm Renice
alters the 
scheduling priority of one or more running processes.
The following
.Ar who
parameters are interpreted as process ID's, process group
ID's, or user names.
.Nm Renice Ns 'ing
a process group causes all processes in the process group
to have their scheduling priority altered.  
.Nm Renice Ns '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.
.Pp
Options supported by
.Nm renice :
.Bl -tag -width Ds
.It Fl g
Force 
.Ar who
parameters to be interpreted as process group ID's.
.It Fl u
Force the
.Ar who
parameters to be interpreted as user names.
.It Fl p
Resets the
.Ar who
interpretation to be (the default) process ID's.
.El
.Pp
For example,
.Bd -literal -offset
renice +1 987 -u daemon root -p 32
.Ed
.Pp
would change the priority of process ID's 987 and 32, and
all processes owned by users daemon and root.
.Pp
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
.Dv 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
.Dv PRIO_MIN
(\-20)
to
.Dv 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).
.Sh FILES
.Bl -tag -width /etc/passwd -compact
.It Pa /etc/passwd
to map user names to user ID's
.El
.Sh SEE ALSO
.Xr getpriority 2 ,
.Xr setpriority 2
.Sh 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.
.br
The Linux kernel (at least version 2.0.0) and linux libc (at least
version 5.2.18) does not agree entierly on what the specifics of the
systemcall interface to set nice values is.  Thus causes renice to
report bogus previous nice values.
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.0 .