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.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright (c) 1992 Drew Eckhardt <drew@cs.colorado.edu>, March 28, 1992
.\"
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.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
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.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Modified by Michael Haardt <michael@moria.de>
.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
.\" Modified 1996-11-04 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 2001-06-04 by aeb
.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" Japanese Version Copyright (c) 1997 SUTO, Mitsuaki
.\"         all rights reserved.
.\" Translated 1997-06-26, SUTO, Mitsuaki <suto@av.crl.sony.co.jp>
.\" Updated 2001-06-25, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2005-09-03, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2005-10-07, Akihiro MOTOKI
.\"
.TH NICE 2 2007-07-26 "Linux" "Linux Programmer's Manual"
.SH ̾Á°
nice \- ¥×¥í¥»¥¹¤ÎÍ¥ÀèÅÙ¤òÊѹ¹¤¹¤ë
.SH ½ñ¼°
.B #include <unistd.h>
.sp
.BI "int nice(int " inc );
.sp
.in -4n
.\"O Feature Test Macro Requirements for glibc (see
.\"O .BR feature_test_macros (7)):
glibc ¸þ¤±¤Îµ¡Ç½¸¡ºº¥Þ¥¯¥í¤ÎÍ×·ï
.RB ( feature_test_macros (7)
»²¾È):
.in
.sp
.BR nice ():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE
.\"O .SH DESCRIPTION
.SH ÀâÌÀ
.\"O .BR nice ()
.\"O adds
.\"O .I inc
.\"O to the nice value for the calling process.
.\"O (A higher nice value means a low priority.)
.\"O Only the super\%user may specify a negative increment,
.\"O or priority increase.
.\"O The range for nice values is described in
.\"O .BR getpriority (2).
.BR nice ()
¤Ï
.I inc
¤ÎÃͤò
.B nice
¤ò¸Æ¤ó¤À¥×¥í¥»¥¹¤Î nice Ãͤ˲䨤ë
(nice Ãͤ¬Â礭¤¤¿ôÃͤۤÉÄ㤤ͥÀèÅÙ¤òɽ¤¹)¡£
Éé¤Î¿ô¤ò»ØÄꤹ¤ë¡¢¤Ä¤Þ¤ê¡¢°ÊÁ°¤è¤ê¤âÍ¥ÀèÅÙ¤ò¾å¤²¤ë¤È¤¤¤¦»ØÄ꤬¤Ç¤­¤ë¤Î¤Ï
¥¹¡¼¥Ñ¡¼¥æ¡¼¥¶¡¼¤À¤±¤Ç¤¢¤ë¡£
nice ÃͤÎÈϰϤˤĤ¤¤Æ¤Ï
.BR getpriority (2)
¤ÇÀâÌÀ¤µ¤ì¤Æ¤¤¤ë¡£
.\"O .SH "RETURN VALUE"
.SH ÊÖ¤êÃÍ
.\"O On success, the new nice value is returned (but see NOTES below).
.\"O On error, \-1 is returned, and
.\"O .I errno
.\"O is set appropriately.
À®¸ù¤·¤¿¾ì¹ç¡¢¿·¤·¤¤ nice Ãͤ¬ÊÖ¤ë (⤷¡¢²¼µ­¤Î¡ÖÃí°Õ¡×¤ò»²¾È)¡£
¼ºÇÔ¤·¤¿¾ì¹ç \-1 ¤¬Ê֤ꡢ
.I errno
¤¬¥¨¥é¡¼¤ÎÆâÍƤ˽¾¤Ã¤ÆÀßÄꤵ¤ì¤ë¡£
.\"O .SH ERRORS
.SH ¥¨¥é¡¼
.TP
.B EPERM
.\"O A non-super user attempts to do a priority increase
.\"O by supplying a negative
¥¹¡¼¥Ñ¡¼¥æ¡¼¥¶¡¼°Ê³°¤¬
.I inc
¤ËÉé¤Î¿ôÃͤò»ØÄꤷ¤ÆÍ¥ÀèÅÙ¤ò¾å¤²¤è¤¦¤È¤·¤¿¡£
.\"O The calling process attempted to increase its priority by
.\"O supplying a negative
.\"O .I inc
.\"O but has insufficient privileges.
.\"O Under Linux the
.\"O .B CAP_SYS_NICE
.\"O capability is required.
.\"O (But see the discussion of the
.\"O .B RLIMIT_NICE
.\"O resource limit in
.\"O .BR setrlimit (2).)
¸Æ¤Ó½Ð¤·¸µ¤Î¥×¥í¥»¥¹¤¬
.I inc
¤ËÉé¤Î¿ôÃͤò»ØÄꤷ¤ÆÍ¥ÀèÅÙ¤ò¾å¤²¤è¤¦¤È¤·¤¿¤¬¡¢
½½Ê¬¤Ê¸¢¸Â¤ò»ý¤Ã¤Æ¤¤¤Ê¤«¤Ã¤¿¡£
Linux ¤Ç¤Ï
.B CAP_SYS_NICE
¥±¡¼¥Ñ¥Ó¥ê¥Æ¥£¤¬É¬ÍפǤ¢¤ë¡£
.RB ( setrlimit (2)
¤Î¥ê¥½¡¼¥¹¾å¸Â
.B RLIMIT_NICE
¤Ë´Ø¤¹¤ëµÄÏÀ¤â»²¾È¤Î¤³¤È)¡£
.\"O .SH "CONFORMING TO"
.SH ½àµò
.\"O SVr4, 4.3BSD, POSIX.1-2001.
.\"O However, the Linux and (g)libc
.\"O (earlier than glibc 2.2.4) return value is nonstandard, see below.
.\"O SVr4 documents an additional
.\"O .B EINVAL
.\"O error code.
SVr4, 4.3BSD, POSIX.1-2001.
¤·¤«¤·¡¢Linux ¤È (2.2.4¤è¤ê¸Å¤¤) (g)libc ¤Ç¤ÏÊÖ¤êÃͤÏɸ½à¤È°Û¤Ê¤ë¡£
¾ÜºÙ¤Ï°Ê²¼¤ò»²¾È¤Î¤³¤È¡£
SVr4 ¤Ë¤Ï¾¤Ë
.B EINVAL
¥¨¥é¡¼¥³¡¼¥É¤Ë¤Ä¤¤¤Æ¤Îµ­½Ò¤¬¤¢¤ë¡£
.\"O .SH NOTES
.SH Ãí°Õ
.\"O SUSv2 and POSIX.1-2001 specify that
.\"O .BR nice ()
.\"O should return the new nice value.
.\"O However, the Linux syscall and the
.\"O .BR nice ()
.\"O library function provided in older versions of (g)libc
.\"O (earlier than glibc 2.2.4) return 0 on success.
.\"O The new nice value can be found using
.\"O .BR getpriority (2).
SUSv2 ¤È POSIX 1003.1-2003 ¤Ç¤Ï¡¢
.BR nice ()
¤Ï¿·¤·¤¤ nice ÃͤòÊÖ¤¹¤Èµ¬Äꤵ¤ì¤Æ¤¤¤ë¡£
°ìÊý¡¢Linux ¥·¥¹¥Æ¥à¥³¡¼¥ë¤È (2.2.4 ¤è¤ê¸Å¤¤) (g)libc ¥é¥¤¥Ö¥é¥ê´Ø¿ô¤Ï
À®¸ù»þ¤Ë 0 ¤òÊÖ¤¹¡£¿·¤·¤¤ nice ÃͤÏ
.BR getpriority (2)
¤ò»È¤Ã¤Æ¼èÆÀ¤Ç¤­¤ë¡£

.\"O Since glibc 2.2.4,
.\"O .BR nice ()
.\"O is implemented as a library function that calls
.\"O .BR getpriority (2)
.\"O to obtain the new nice value to be returned to the caller.
.\"O With this implementation,
.\"O a successful call can legitimately return \-1.
glibc 2.2.4 °Ê¹ß¤Ç¤Ï¡¢
.BR nice ()
¤Ï
.BR getpriority (2)
¤ò¸Æ¤Ó½Ð¤¹¥é¥¤¥Ö¥é¥ê´Ø¿ô¤È¤·¤Æ¼ÂÁõ¤µ¤ì¤Æ¤ª¤ê¡¢
¸Æ¤Ó½Ð¤·¸µ¤ËÊÖ¤¹¿·¤·¤¤ nice Ãͤò
.BR getpriority (2)
¤ò¸Æ¤Ó½Ð¤·¤Æ¼èÆÀ¤¹¤ë¤è¤¦¤Ë¤Ê¤Ã¤Æ¤¤¤ë¡£
¤³¤Î¼ÂÁõ¤Ç¤Ï¡¢Àµ¾ï¤ÊÆ°ºî¤Ç¤â \-1 ¤¬ÊÖ¤µ¤ì¤ë²ÄǽÀ­¤¬¤¢¤ë¡£
.\"O To reliably detect an error, set
.\"O .I errno
.\"O to 0 before the call, and check its value when
.\"O .BR nice ()
.\"O returns \-1.
³Î¼Â¤Ë¥¨¥é¡¼¤ò¸¡½Ð¤¹¤ë¤¿¤á¤Ë¤Ï¡¢
¸Æ¤Ó½Ð¤·¤ÎÁ°¤Ë
.I errno
¤Ë 0 ¤òÀßÄꤷ¡¢
.BR nice ()
¤¬ \-1 ¤òÊÖ¤·¤¿¤È¤­¤Ë errno ¤ò¥Á¥§¥Ã¥¯¤¹¤ë¤ÈÎɤ¤¡£
.\"O .SH "SEE ALSO"
.SH ´ØÏ¢¹àÌÜ
.BR nice (1),
.BR fork (2),
.BR getpriority (2),
.BR setpriority (2),
.BR capabilities (7),
.BR renice (8)