2004-11-03 13:51:07 +00:00
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.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" Copyright (c) 1992 Drew Eckhardt <drew@cs.colorado.edu>, March 28, 1992
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" Modified by Michael Haardt <michael@moria.de>
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.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
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.\" Modified 1996-11-04 by Eric S. Raymond <esr@thyrsus.com>
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.\" Modified 2001-06-04 by aeb
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2004-11-03 14:43:40 +00:00
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.\" Modified 2004-05-27 by Michael Kerrisk <mtk-manpages@gmx.net>
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2004-11-03 13:51:07 +00:00
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.\"
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.TH NICE 2 2004-05-27 "Linux 2.6.6" "Linux Programmer's Manual"
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.SH NAME
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nice \- change process priority
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.SH SYNOPSIS
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.B #include <unistd.h>
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.sp
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.BI "int nice(int " inc );
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.SH DESCRIPTION
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.B nice
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adds
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.I inc
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to the nice value for the calling pid.
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(A large nice value means a low priority.)
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Only the super\%user may specify a negative increment, or priority increase.
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.SH "RETURN VALUE"
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On success, zero is returned. On error, \-1 is returned, and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EPERM
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The calling process attempted to increase its priority by
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supplying a negative
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.IR inc
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but has insufficient privileges.
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Under Linux the
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.B CAP_SYS_NICE
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capability is required.
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.SH "CONFORMING TO"
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SVr4, SVID EXT, AT&T, X/OPEN, BSD 4.3. However, the Linux and glibc
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(earlier than glibc 2.2.4) return value is nonstandard, see below.
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SVr4 documents an additional
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EINVAL error code.
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.SH NOTES
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Note that the routine is documented in SUSv2 and POSIX 1003.1-2003
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to return the new nice value, while the Linux syscall and (g)libc
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(earlier than glibc 2.2.4) routines return 0 on success.
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The new nice value can be found using
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.BR getpriority (2).
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Note that an implementation in which
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.B nice
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returns the new nice value can legitimately return \-1.
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To reliably detect an error, set
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.I errno
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to 0 before the call, and check its value when
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.B nice
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returns \-1.
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.SH "SEE ALSO"
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.BR nice (1),
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.BR fork (2),
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.BR getpriority (2),
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.BR setpriority (2),
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.BR capabilities (7),
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.BR renice (8)
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