nice.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)nice.1	8.1	9/11/90
.TH nice 1 
.SH Name
nice, nohup \- execute a command at a lower priority 
.SH Syntax
.B nice
[\fB\-\fInumber\fR\|] \fIcommand\fR [\|\fIarguments\fR\|]
.PP
.B nohup
\fIcommand\fR [\|\fIarguments\|\fR]
.SH Description
.NXR "nice command (sh)"
.NXR "nohup command (sh)"
.NXR "priority" "setting low"
The
.PN nice
command executes
.I command
with low scheduling priority (Bourne Shell only).
If the
.I number
argument is present, the priority is incremented (higher
numbers mean lower priorities) by that amount up to a limit of 20.
The default
.I number
is 10.
.PP
The super-user may run commands with
priority higher than normal
by using a negative priority,
for example, `\-\-10'.
.PP
The
.PN nohup
command executes
.I command
immune to hangup and terminate signals from the controlling terminal.
The priority is incremented by 5.
The
.PN nohup
command should be invoked from the shell with an ampersand (&) in order to 
prevent it from responding to interrupts by or
stealing the input from
the next person who logs in on the same terminal.
The syntax of 
.PN nice
is also different.
.SH Options
.IP \fB\-\fInumber\fR 20
Increments the priority by a specified number up to a limit of
20.  The default is 10.
.SH Restrictions
The
.PN nice
and
.PN nohup
commands are particular to 
.MS sh 1 .
If you use 
.MS csh 1 ,
then commands executed with an ampersand (&) are automatically 
immune to hangup signals while in the background.
There is a built-in command
.PN nohup
which provides immunity from terminate, but it does not
redirect output to nohup.out.
.PP
The
.PN nice
command is built into 
.MS csh 1
with a slightly different syntax than described here.  The form
``nice +10'' nices to positive nice, and ``nice \-10'' can be used
by the superuser to give a process more of the processor.
.SH Diagnostics
The
.PN nice
command returns the exit status of the subject command.
.SH Files
nohup.out	standard output and standard error file under nohup
.SH See Also
csh(1), getpriority(2), renice(8)