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[linuxjm/LDP_man-pages.git] / draft / man2 / shmget.2

.\" Copyright (c) 1993 Luigi P. Bai (lpb@softint.com) July 28, 1993
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" 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
.\" permission notice identical to this one.
.\"
.\" 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.\" manual page may be incorrect or out-of-date.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 Wed Jul 28 10:57:35 1993, Rik Faith <faith@cs.unc.edu>
.\" Modified Sun Nov 28 16:43:30 1993, Rik Faith <faith@cs.unc.edu>
.\"          with material from Giorgio Ciucci <giorgio@crcc.it>
.\" Portions Copyright 1993 Giorgio Ciucci <giorgio@crcc.it>
.\" Modified Tue Oct 22 22:03:17 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified, 8 Jan 2003, Michael Kerrisk, <mtk.manpages@gmail.com>
.\"     Removed EIDRM from errors - that can't happen...
.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
.\"     Added notes on capability requirements
.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
.\"     Language and formatting clean-ups
.\"     Added notes on /proc files
.\"
.\" Japanese Version Copyright (c) 1997 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated 1997-03-01, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated & Modified 2001-06-03, Yuichi SATO <ysato@h4.dion.ne.jp>
.\" Updated 2001-12-22, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2002-10-16, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2003-02-23, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2005-03-02, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2005-11-04, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2006-07-21, Akihiro MOTOKI, LDP v2.36
.\"
.\"WORD:        shared memory           ¶¦Í­¥á¥â¥ê
.\"WORD:        segment                 ¥»¥°¥á¥ó¥È
.\"WORD:        owner                   ½êÍ­¼Ô
.\"WORD:        group                   ¥°¥ë¡¼¥×
.\"WORD:        world                   ¾¿Í
.\"WORD:        creator                 ºîÀ®¼Ô
.\"WORD:        super-user              ¥¹¡¼¥Ñ¡¼¡¦¥æ¡¼¥¶¡¼
.\"WORD:        detach                  ʬΥ
.\"WORD:        attach                  ÉÕ²Ã
.\"WORD:        identifier              ¼±ÊÌ»Ò
.\"WORD:        member                  ¥á¥ó¥Ð¡¼
.\"WORD:        effective user ID       ¼Â¸ú¥æ¡¼¥¶¡¼ID
.\"WORD:        effective group ID      ¼Â¸ú¥°¥ë¡¼¥×ID
.\"WORD:        policy                  Êý¿Ë
.\"WORD:        implement               ¼ÂÁõ
.\"
.TH SHMGET 2 2006-05-02 "Linux" "Linux Programmer's Manual"
.\"O .SH NAME
.SH ̾Á°
.\"O shmget \- allocates a shared memory segment
shmget \- ¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤ò³ä¤êÅö¤Æ¤ë
.\"O .SH SYNOPSIS
.SH ½ñ¼°
.ad l
.B #include <sys/ipc.h>
.br
.B #include <sys/shm.h>
.sp
.BI "int shmget(key_t " key ", size_t " size ", int " shmflg );
.ad b
.\"O .SH DESCRIPTION
.SH ÀâÌÀ
.\"O .BR shmget ()
.\"O returns the identifier of the shared memory segment
.\"O associated with the value of the argument
.\"O .IR key .
.\"O A new shared memory segment, with size equal to the value of
.\"O .I size
.\"O rounded up to a multiple of
.\"O .BR PAGE_SIZE ,
.\"O is created if
.\"O .I key
.\"O has the value
.\"O .B IPC_PRIVATE
.\"O or
.\"O .I key
.\"O isn't
.\"O .BR IPC_PRIVATE ,
.\"O no shared memory segment corresponding to
.\"O .I key
.\"O exists, and
.\"O .B IPC_CREAT
.\"O is specified in
.\"O .IR shmflg .
.BR shmget ()
¤Ï
.I key
°ú¤­¿ô¤ËÂбþ¤¹¤ë¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤Î¼±Ê̻ҤòÊÖ¤¹¡£
.I key
¤ÎÃͤ¬
.B IPC_PRIVATE
¤Î¾ì¹ç¡¢¤â¤·¤¯¤Ï
.I key
¤ËÂбþ¤¹¤ë¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤¬Â¸ºß¤»¤º¡¢
.I shmflg
¤Ë
.B IPC_CREAT
¤¬»ØÄꤵ¤ì¤Æ¤¤¤¿¾ì¹ç¡¢
¿·¤·¤¤¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤òºîÀ®¤¹¤ë¡£
ºîÀ®¤µ¤ì¤ë¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤Ï¡¢
.I size
°ú¤­¿ô¤ÎÃͤò
.B PAGE_SIZE
¤ÎÇÜ¿ô¤Ø¤ÈÀÚ¤ê¾å¤²¤¿ (round up) Â礭¤µ¤È¤Ê¤ë¡£
.PP
.\"O If
.\"O .I shmflg
.\"O specifies both
.\"O .B IPC_CREAT
.\"O and
.\"O .B IPC_EXCL
.\"O and a shared memory segment already exists for
.\"O .IR key ,
.\"O then
.\"O .BR shmget ()
.\"O fails with
.\"O .I errno
.\"O set to
.\"O .BR EEXIST .
.\"O (This is analogous to the effect of the combination
.\"O .B O_CREAT | O_EXCL
.\"O for
.\"O .BR open (2).)
.I shmflg
¤Ë
.B IPC_CREAT
¤È
.B IPC_EXCL
¤ÎξÊý¤¬»ØÄꤵ¤ì¤¿¾ì¹ç¡¢
.I key
¤ËÂбþ¤¹¤ë¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤¬´û¤Ë¸ºß¤¹¤ë¤È¡¢
.BR shmget ()
¤Ï¼ºÇÔ¤·¡¢
.I errno
¤Ë
.B EEXIST
¤¬ÀßÄꤵ¤ì¤ë (¤³¤ì¤Ï
.BR open (2)
¤Ë
.B O_CREAT | O_EXCL
¤ò»ØÄꤷ¤¿¾ì¹ç¤ÎÆ°ºî¤ÈƱ¤¸¤Ç¤¢¤ë)¡£
.PP
.\"O The value
.\"O .I shmflg
.\"O is composed of:
.I shmflg
¤Ï°Ê²¼¤ÎÆâÍƤ«¤é¹½À®¤µ¤ì¤ë:
.TP 12
.B IPC_CREAT
.\"O to create a new segment.
.\"O If this flag is not used, then
.\"O .BR shmget ()
.\"O will find the segment associated with \fIkey\fP and check to see if
.\"O the user has permission to access the segment.
¿·¤·¤¤¥»¥°¥á¥ó¥È¤òºîÀ®¤¹¤ë¡£¤³¤Î¥Õ¥é¥°¤¬»ØÄꤵ¤ì¤Ê¤«¤Ã¤¿¾ì¹ç¡¢
.BR shmget ()
¤Ï \fIkey\fP ¤ËÂбþ¤¹¤ë¥»¥°¥á¥ó¥È¤òõ¤·¡¢
¥æ¡¼¥¶¤¬¤½¤Î¥»¥°¥á¥ó¥È¤Ë¥¢¥¯¥»¥¹¤¹¤ëµö²Ä¤¬¤¢¤ë¤«¤É¤¦¤«¤ò¥Á¥§¥Ã¥¯¤¹¤ë¡£
.TP
.B IPC_EXCL
.\"O used with \fBIPC_CREAT\fP to ensure failure if the segment already exists.
\fBIPC_CREAT\fP ¤È¶¦¤Ë»ÈÍѤ·¡¢¥»¥°¥á¥ó¥È¤¬´û¤Ë¸ºß¤·¤¿¾ì¹ç¤Ë¤Ï
¼ºÇÔ¤¹¤ë¤³¤È¤òÊݾڤ¹¤ë¡£
.TP
.I mode_flags
.\"O (least significant 9 bits)
(²¼°Ì 9 ¥Ó¥Ã¥È)
.\"O specifying the permissions granted to the owner, group, and world.
.\"O These bits have the same format, and the same
.\"O meaning, as the
.\"O .I mode
.\"O argument of
.\"O .BR open (2).
.\"O Presently, the execute permissions are not used by the system.
½êÍ­¼Ô¡¢¥°¥ë¡¼¥×¡¢Â¾¿Í (world) ¤Ø¤Îµö²Ä¤ò»ØÄꤹ¤ë¡£
¤³¤ì¤é¤Î¥Ó¥Ã¥È¤Ï
.BR open (2)
¤Î
.I mode
°ú¤­¿ô¤ÈƱ¤¸·Á¼°¤ÇƱ¤¸°ÕÌ£¤ò»ý¤Ä¡£
º£¤Î¤È¤³¤í¡¢¥·¥¹¥Æ¥à¤Ï¼Â¹Ô (execute) µö²Ä¤ò»²¾È¤·¤Ê¤¤¡£
.TP
.\"O .BR SHM_HUGETLB " (since Linux 2.6)"
.BR SHM_HUGETLB " (Linux 2.6 °Ê¹ß)"
.\"O Allocate the segment using "huge pages."
.\"O See the kernel source file
.\"O .I Documentation/vm/hugetlbpage.txt
.\"O for further information.
"¥Ò¥å¡¼¥¸¥Ú¡¼¥¸ (huge page)" ¤ò»È¤¦¥»¥°¥á¥ó¥È¤ò³ä¤êÅö¤Æ¤ë¡£
¾ÜºÙ¤Ê¾ðÊó¤Ï¡¢¥«¡¼¥Í¥ë¡¦¥½¡¼¥¹¤Î¥Õ¥¡¥¤¥ë
.I Documentation/vm/hugetlbpage.txt
¤ò»²¾È¡£
.TP
.\"O .BR SHM_NORESERVE " (since Linux 2.6.15)"
.BR SHM_NORESERVE " (Linux 2.6.15 °Ê¹ß)"
.\"O This flag serves the same purpose as the
.\"O .BR mmap (2)
.\"O .B MAP_NORESERVE
.\"O flag.
¤³¤Î¥Õ¥é¥°¤Ï¡¢
.BR mmap (2)
¤Î
.B MAP_NORESERVE
¥Õ¥é¥°¤ÈƱ¤¸Ìò³ä¤ò²Ì¤¿¤¹¡£
.\"O Do not reserve swap space for this segment.
.\"O When swap space is reserved, one has the guarantee
.\"O that it is possible to modify the segment.
.\"O When swap space is not reserved one might get
.\"O .B SIGSEGV
.\"O upon a write
.\"O if no physical memory is available.
¤³¤Î¥»¥°¥á¥ó¥È¤ËÂФ¹¤ë¥¹¥ï¥Ã¥×¶õ´Ö¤ÎͽÌó¤ò¹Ô¤ï¤Ê¤¤¡£
¥¹¥ï¥Ã¥×¶õ´Ö¤òͽÌó¤·¤¿¾ì¹ç¤Ï¡¢¤½¤Î¥»¥°¥á¥ó¥È¤ÎÊѹ¹¤¬É¬¤ºÀ®¸ù¤¹¤ë¤³¤È¤¬
Êݾڤµ¤ì¤ë¡£¥¹¥ï¥Ã¥×¶õ´Ö¤ÎͽÌó¤ò¹Ô¤ï¤Ê¤«¤Ã¤¿¾ì¹ç¤Ï¡¢ÊªÍý¥á¥â¥ê¤Ë¶õ¤­¤¬
¤Ê¤¤¤È½ñ¤­¹þ¤ß»þ¤Ë
.B SIGSEGV
¤ò¼õ¤±¼è¤ë²ÄǽÀ­¤¬¤¢¤ë¡£
.\"O See also the discussion of the file
.\"O .I /proc/sys/vm/overcommit_memory
.\"O in
.\"O .BR proc (5).
.BR proc (5)
¤Ë¤¢¤ë
.I /proc/sys/vm/overcommit_memory
¥Õ¥¡¥¤¥ë¤Ë´Ø¤¹¤ëµÄÏÀ¤â»²¾È¤Î¤³¤È¡£
.\" As at 2.6.17-rc2, this flag has no effect if SHM_HUGETLB was also
.\" specified.
.PP
.\"O When a new shared memory segment is created,
.\"O its contents are initialized to zero values, and
.\"O its associated data structure,
.\"O .I shmid_ds
.\"O (see
.\"O .BR shmctl (2)),
.\"O is initialized as follows:
¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤¬¿·¤¿¤ËºîÀ®¤µ¤ì¤ëºÝ¡¢
¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤ÎÆâÍÆ¤Ï 0 ¤Ç½é´ü²½¤µ¤ì¡¢
´ØÏ¢¾ðÊó¤òÊÝ»ý¤¹¤ë¥Ç¡¼¥¿¹½Â¤ÂÎ
.I shmid_ds
¤Ï°Ê²¼¤Î¤è¤¦¤Ë½é´ü²½¤µ¤ì¤ë¡£
.IP
.\"O .I shm_perm.cuid
.\"O and
.\"O .I shm_perm.uid
.\"O are set to the effective user ID of the calling process.
.I shm_perm.cuid
¤È
.I shm_perm.uid
¤Ë¸Æ¤Ó½Ð¤·¸µ¥×¥í¥»¥¹¤Î¼Â¸ú (effective) ¥æ¡¼¥¶¡¼ID ¤òÀßÄꤹ¤ë¡£
.IP
.\"O .I shm_perm.cgid
.\"O and
.\"O .I shm_perm.gid
.\"O are set to the effective group ID of the calling process.
.I shm_perm.cgid
¤È
.I shm_perm.gid
¤Ë¸Æ¤Ó½Ð¤·¸µ¥×¥í¥»¥¹¤Î¼Â¸ú¥°¥ë¡¼¥×ID ¤òÀßÄꤹ¤ë¡£
.IP
.\"O The least significant 9 bits of
.\"O .I shm_perm.mode
.\"O are set to the least significant 9 bit of
.\"O .IR shmflg .
.I shm_perm.mode
¤Î²¼°Ì 9 ¥Ó¥Ã¥È¤Ë
.I shmflg
¤Î²¼°Ì 9 ¥Ó¥Ã¥È¤òÀßÄꤹ¤ë¡£
.IP
.\"O .I shm_segsz
.\"O is set to the value of
.\"O .IR size .
.I shm_segsz
¤Ë
.I size
¤ÎÃͤòÀßÄꤹ¤ë¡£
.IP
.\"O .IR shm_lpid ,
.\"O .IR shm_nattch ,
.\"O .I shm_atime
.\"O and
.\"O .I shm_dtime
.\"O are set to 0.
.IR shm_lpid ,
.IR shm_nattch ,
.IR shm_atime ,
.I shm_dtime
¤Ë 0 ¤òÀßÄꤹ¤ë¡£
.IP
.\"O .I shm_ctime
.\"O is set to the current time.
.I shm_ctime
¤Ë¸½ºß¤Î»þ¹ï¤òÀßÄꤹ¤ë¡£
.PP
.\"O If the shared memory segment already exists, the permissions are
.\"O verified, and a check is made to see if it is marked for destruction.
¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤¬´û¤Ë¸ºß¤¹¤ë¾ì¹ç¡¢¥¢¥¯¥»¥¹µö²Ä¤Î¸¡ºº¤È¡¢
Ç˲õ (destruction) ¥Þ¡¼¥¯¤¬¤Ä¤±¤é¤ì¤Æ¤¤¤Ê¤¤¤«¤Î¥Á¥§¥Ã¥¯¤¬¹Ô¤ï¤ì¤ë¡£
.\"O .SH "RETURN VALUE"
.SH ÊÖ¤êÃÍ
.\"O A valid segment identifier,
.\"O .IR shmid ,
.\"O is returned on success, \-1 on error.
À®¸ù¤·¤¿¾ì¹ç¡¢Í­¸ú¤Ê¥»¥°¥á¥ó¥È¼±ÊÌ»Ò
.I shmid
¤¬ÊÖ¤µ¤ì¤ë¡£¥¨¥é¡¼¤Î¾ì¹ç¡¢ \-1 ¤¬ÊÖ¤µ¤ì¤ë¡£
.\"O .SH ERRORS
.SH ¥¨¥é¡¼
.\"O On failure,
.\"O .I errno
.\"O is set to one of the following:
¼ºÇÔ¤·¤¿¾ì¹ç¤Ï
.I errno
¤¬°Ê²¼¤Î¤É¤ì¤«¤ËÀßÄꤵ¤ì¤ë:
.TP
.B EACCES
.\"O The user does not have permission to access the
.\"O shared memory segment, and does not have the
.\"O .B CAP_IPC_OWNER
.\"O capability.
¥æ¡¼¥¶¡¼¤Ï¤½¤Î¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤Ø¤Î¥¢¥¯¥»¥¹µö²Ä¤ò»ý¤¿¤º¡¢
.B CAP_IPC_OWNER
¥±¡¼¥Ñ¥Ó¥ê¥Æ¥£¤â»ý¤Ã¤Æ¤¤¤Ê¤¤¡£
.TP
.B EEXIST
.\"O .B IPC_CREAT | IPC_EXCL
.\"O was specified and the segment exists.
.B IPC_CREAT | IPC_EXCL
¤¬»ØÄꤵ¤ì¤Æ¤¤¤¿¤¬¡¢¤½¤Î¥»¥°¥á¥ó¥È¤¬´û¤Ë¸ºß¤¹¤ë¡£
.TP
.B EINVAL
.\"O A new segment was to be created and \fIsize\fP < \fBSHMMIN\fP
.\"O or \fIsize\fP > \fBSHMMAX\fP, or no new segment was to be created,
.\"O a segment with given key existed, but \fIsize\fP is greater than the size
.\"O of that segment.
¿·¤·¤¤¥»¥°¥á¥ó¥È¤òºîÀ®¤·¤è¤¦¤È¤·¤¿ºÝ¤Ë
\fIsize\fP < \fBSHMMIN\fP ¤Þ¤¿¤Ï \fIsize\fP > \fBSHMMAX\fP ¤Ç¤¢¤Ã¤¿¡£
¤â¤·¤¯¤Ï¡¢»ØÄꤵ¤ì¤¿¥­¡¼¤ËÂбþ¤¹¤ë¥»¥°¥á¥ó¥È¤¬´û¤Ë¸ºß¤·¤Æ¡¢¿·¤·¤¤
¥»¥°¥á¥ó¥È¤òºîÀ®¤·¤è¤¦¤È¤Ï¤·¤Ê¤«¤Ã¤¿¤¬¡¢\fIsize\fP ¤¬Â¸ºß¤¹¤ë¥»¥°¥á¥ó¥È¤Î
¥µ¥¤¥º¤è¤ê¤âÂ礭¤«¤Ã¤¿¡£
.TP
.B ENFILE
.\"O .\" [2.6.7] shmem_zero_setup()-->shmem_file_setup()-->get_empty_filp()
.\"O The system limit on the total number of open files has been reached.
.\" [2.6.7] shmem_zero_setup()-->shmem_file_setup()-->get_empty_filp()
¥·¥¹¥Æ¥àÁ´ÂΤǥª¡¼¥×¥ó¤µ¤ì¤Æ¤¤¤ë¥Õ¥¡¥¤¥ë¤ÎÁí¿ô¤¬¾å¸Â¤Ë㤷¤¿¡£
.TP
.B ENOENT
.\"O No segment exists for the given \fIkey\fP, and
.\"O .B IPC_CREAT
.\"O was not specified.
»ØÄꤵ¤ì¤¿ \fIkey\fP ¤ËÂбþ¤¹¤ë¥»¥°¥á¥ó¥È¤¬Â¸ºß¤»¤º¡¢
.B IPC_CREAT
¤â»ØÄꤵ¤ì¤Æ¤¤¤Ê¤«¤Ã¤¿¡£
.TP
.B ENOMEM
.\"O No memory could be allocated for segment overhead.
¥»¥°¥á¥ó¥È¤Î´ÉÍý¾ðÊó (overhead) ¤Ë³ä¤êÅö¤Æ¤ë¥á¥â¥ê¤¬¤Ê¤«¤Ã¤¿¡£
.TP
.B ENOSPC
.\"O All possible shared memory ID's have been taken
.\"O .RB ( SHMMNI ),
.\"O or allocating a segment of the requested
.\"O .I size
.\"O would cause the system to exceed the system-wide limit on shared memory
.\"O .RB ( SHMALL ).
.\" motoki 2005-03-02 -- SHMMNI ¤Î°ÕÌ£¤ò¹Íθ¤·¤Æ°ÕÌõ
¥·¥¹¥Æ¥àÁ´ÂΤζ¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¿ô¤ÎÀ©¸Â
.RB ( SHMMNI )
¤Ë㤷¤¿¡¢¤Þ¤¿¤ÏÍ׵ᤵ¤ì¤¿
.I size
¤Î¥»¥°¥á¥ó¥È¤Î³ä¤êÅö¤Æ¤¬
¥·¥¹¥Æ¥àÁ´ÂΤζ¦Í­¥á¥â¥ê¥µ¥¤¥º¤ÎÀ©¸Â
.RB ( SHMALL )
¤òĶ²á¤·¤¿¡£
.TP
.B EPERM
.\"O The
.\"O .B SHM_HUGETLB
.\"O flag was specified, but the caller was not privileged (did not have the
.\"O .B CAP_IPC_LOCK
.\"O capability).
.B SHM_HUGETLB
¥Õ¥é¥°¤¬»ØÄꤵ¤ì¤¿¤¬¡¢¸Æ¤Ó½Ð¤·¸µ¤Ë¤Ï¸¢¸Â¤¬¤Ê¤«¤Ã¤¿
.RB ( CAP_IPC_LOCK
¥±¡¼¥Ñ¥Ó¥ê¥Æ¥£¤ò»ý¤Ã¤Æ¤¤¤Ê¤«¤Ã¤¿)¡£
.\"O .SH "CONFORMING TO"
.SH ½àµò
SVr4, POSIX.1-2001.
.\"O .\" SVr4 documents an additional error condition EEXIST.
.\" SVr4 ¤Ë¤ÏÄÉ²Ã¤Ç EEXIST ¥¨¥é¡¼¾õÂ֤ε­½Ò¤¬¤¢¤ë¡£

.\"O .B SHM_HUGETLB
.\"O is a nonportable Linux extension.
.B SHM_HUGETLB
¤Ï Linux ¤Ç¤Î³ÈÄ¥¤Ç¤¢¤ê¡¢°Ü¿¢À­¤Ï¤Ê¤¤¡£
.\"O .SH NOTES
.SH Ãí°Õ
.\"O .B IPC_PRIVATE
.\"O isn't a flag field but a
.\"O .I key_t
.\"O type.
.B IPC_PRIVATE
¤Ï¥Õ¥é¥°¤Ç¤Ï¤Ê¤¯
.I key_t
·¿¤Ç¤¢¤ë¡£
.\"O If this special value is used for
.\"O .IR key ,
.\"O the system call ignores everything but the least significant 9 bits of
.\"O .I shmflg
.\"O and creates a new shared memory segment (on success).
¤³¤ÎÆÃÊ̤ÊÃͤ¬
.I key
¤Ë»ÈÍѤµ¤ì¤¿¾ì¹ç¤Ï¡¢
.BR shmget ()
¤Ï
.I shmflg
¤Î²¼°Ì 9 ¥Ó¥Ã¥È¤ò½ü¤¤¤¿Á´¤Æ¤ò̵»ë¤·¡¢
(À®¸ù¤¹¤ì¤Ð) ¿·¤·¤¤¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤òºîÀ®¤¹¤ë¡£
.PP
.\"O The following limits on shared memory segment resources affect the
.\"O .BR shmget ()
.\"O call:
.BR shmget ()
¥³¡¼¥ë¤Ë±Æ¶Á¤¹¤ë¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È»ñ¸»¤ÎÀ©¸Â¤Ï°Ê²¼¤ÎÄ̤ê¤Ç¤¢¤ë:
.TP
.B SHMALL
.\"O System wide maximum of shared memory pages
.\"O (on Linux, this limit can be read and modified via
.\"O .IR /proc/sys/kernel/shmall ).
¥·¥¹¥Æ¥àÁ´ÂΤζ¦Í­¥á¥â¥ê¡¦¥Ú¡¼¥¸¤ÎºÇÂç¿ô
(Linux ¤Ç¤Ï¡¢¤³¤Î¾å¸ÂÃͤÏ
.I /proc/sys/kernel/shmall
·Ðͳ¤Ç»²¾È¤·¤¿¤ê¡¢Êѹ¹¤·¤¿¤ê¤Ç¤­¤ë)¡£
.TP
.B SHMMAX
.\"O Maximum size in bytes for a shared memory segment: policy dependent
.\"O (on Linux, this limit can be read and modified via
.\"O .IR /proc/sys/kernel/shmmax ).
¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤Î¥Ð¥¤¥Èñ°Ì¤ÎÂ礭¤µ¤Î¾å¸Â: Êý¿Ë°Í¸
(Linux ¤Ç¤Ï¡¢¤³¤Î¾å¸ÂÃͤÏ
.I /proc/sys/kernel/shmmax
·Ðͳ¤Ç»²¾È¤·¤¿¤ê¡¢Êѹ¹¤·¤¿¤ê¤Ç¤­¤ë)¡£
.TP
.B SHMMIN
.\"O Minimum size in bytes for a shared memory segment: implementation
.\"O dependent (currently 1 byte, though
.\"O .B PAGE_SIZE
.\"O is the effective minimum size).
¶¦Í­¥á¥â¥ê¡¦¥»¥°¥á¥ó¥È¤Î¥Ð¥¤¥Èñ°Ì¤ÎÂ礭¤µ¤Î²¼¸Â: ¼ÂÁõ°Í¸
(¸½ºß¤Ï 1 ¥Ð¥¤¥È¤À¤¬¡¢¼Â¼ÁŪ¤ÊºÇ¾®¥µ¥¤¥º¤Ï
.B PAGE_SIZE
¤Ç¤¢¤ë)¡£
.TP
.B SHMMNI
.\"O System wide maximum number of shared memory segments: implementation
.\"O dependent (currently 4096, was 128 before Linux 2.3.99;
.\"O on Linux, this limit can be read and modified via
.\"O .IR /proc/sys/kernel/shmmni ).
.\"O .\" Kernels between 2.4.x and 2.6.8 had an off-by-one error that meant
.\"O .\" that we could create one more segment than SHMMNI -- MTK
.\"O .\" This /proc file is not available in Linux 2.2 and earlier -- MTK
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.\" ¤³¤Î /proc ¥Õ¥¡¥¤¥ë¤Ï Linux 2.2 °ÊÁ°¤Ç¤ÏÍøÍѤǤ­¤Ê¤¤ -- MTK
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.\"O The implementation has no specific limits for the per-process maximum
.\"O number of shared memory segments
.\"O .RB ( SHMSEG ).
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.\"O .SS LINUX NOTES
.\"O Until version 2.3.30 Linux would return
.\"O .B EIDRM
.\"O for a
.\"O .BR shmget ()
.\"O on a shared memory segment scheduled for deletion.
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.\"O .SH BUGS
.SH ¥Ð¥°
.\"O The name choice
.\"O .B IPC_PRIVATE
.\"O was perhaps unfortunate,
.\"O .B IPC_NEW
.\"O would more clearly show its function.
.B IPC_PRIVATE
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.\"O .SH "SEE ALSO"
.SH ´ØÏ¢¹àÌÜ
.BR shmat (2),
.BR shmctl (2),
.BR shmdt (2),
.BR ftok (3),
.BR capabilities (7),
.BR shm_overview (7),
.BR svipc (7)