nice.1

早期freebsd实现

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.\"	@(#)nice.1	8.1 (Berkeley) 6/6/93
.\"
.Dd June 6, 1993
.Dt NICE 1
.Os BSD 4
.Sh NAME
.Nm nice
.Nd execute a command at a low scheduling priority
.Sh SYNOPSIS
.Nm nice
.Op Fl Ns Ar number
.Ar command
.Op Ar arguments
.Sh DESCRIPTION
.Nm Nice
runs
.Ar command
at a low priority.
(Think of low and slow).
If
.Fl Ns Ar number
is specified, and if it is greater than or equal
to 10 (the default),
.Nm nice
will execute
.Ar command
at that priority.
The upper bound, or lowest priority that
.Nm nice
will run a command is 20.
The lower bounds or
higher priorities (integers less than 10)
can only be requested by the super-user.
Negative numbers are expressed as
.Fl - Ns Ar number .
.Pp
The returned exit status is the exit value from the
command executed by
.Nm nice .
.Sh SEE ALSO
.Xr csh 1 ,
.Xr renice 8
.Sh HISTORY
A
.Nm nice
command appeared in
.At v6 .
.Sh BUGS
.Nm Nice
is particular to
.Xr sh  1  .
If you use
.Xr csh  1  ,
then commands executed with ``&'' are automatically immune to hangup
signals while in the background.
.Pp
.Nm Nice
is built into
.Xr csh  1
with a slightly different syntax than described here.  The form
.Ql nice +10
nices to positive nice, and
.Ql nice \-10
can be used
by the super-user to give a process more of the processor.