.\" 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.\" manual page may be incorrect or out-of-date.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>
.\"
.\" Japanese Version Copyright (c) 1997 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated Sat Mar  1 16:51:48 JST 1997
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\"
.\"WORD:	shared memory		ͭ
.\"WORD:	segment			
.\"WORD:	owner			ͭ
.\"WORD:	group			롼
.\"WORD:	world			¾
.\"WORD:	creator			
.\"WORD:	super-user		ѡ桼
.\"WORD:	detach			ʬΥ
.\"WORD:	attach			ղ
.\"WORD:	identifier		̻
.\"WORD:	member			С
.\"WORD:	effective user ID	¸桼ID
.\"WORD:	effective group ID	¸롼ID
.\"WORD:	policy			
.\"WORD:	implement		
.\"
.TH SHMGET 2 "November 28, 1993" "Linux 0.99.11" "Linux Programmer's Manual"
.SH ̾
shmget \- ͭꡦ(shared memory segment)Ƥ
.SH 
.ad l
.B #include <sys/ipc.h>
.sp
.B #include <sys/shm.h>
.sp
.BI "int shmget(key_t " key ", int " size ", int " shmflg );
.ad b
.SH 
.B shmget()

.IR key
ͤ˴Ϣ붦ͭꡦȤμ̻(identifier)
֤⤷ 
.I key
ͤ
.B IPC_PRIVATE
ξϿͭꡦȤ롣
.I key
ͤ
.B IPC_PRIVATE
ǤʤƤ⡢
.IR key
˶ͭꡦȤƤƤ餺
.I shmflg

.B IPC_CREAT
ꤵƤ(
.IB shmflg &IPC_CREAT
Ǥʤ)ˤ
ͭꡦȤ롣
붦ͭꡦȤϰ
.I size

.BR PAGE_SIZE 
ܿؤڤ夲(round up)礭Ȥʤ롣
.PP
.I shmflg
ϰʲƤ鹽:
.TP 12
.B IPC_CREAT
Ȥ롣Υե饰ѤʤäʤС
.B shmget()
 \fIkey\fP ˴Ϣ륻Ȥ򸫤Ĥơ桼Υ
˴Ϣ \fIshmid\fP ȤĤ뤳Ȥå
Ȥ˲(destruction)ޡդƤʤȤݾڤ롣
.TP
.B IPC_EXCL
 \fBIPC_CREAT\fP ȶ˻ѤȤ¸ߤˤ
Ԥ뤳Ȥݾڤ롣
.TP
.B mode_flags (lowest 9 bits)
Ͻͭ(owner)롼(group)¾(world)ؤεĤꤹ롣
ΤȤ¹(execute)ĤϥƥˤäƻѤƤʤ
.PP
⤷Ȥ줿硢
.I shmflg
ΥĤϥȤ
.I shmid_ds
¤Τ
.I shm_perm
Сؤȥԡ롣\fIshmid_ds\fP ¤Τ:
.PP
.in +0.5i
.nf
struct shmid_ds {
	struct	ipc_perm shm_perm;	/* operation perms */
	int	shm_segsz;		/* size of segment (bytes) */
	time_t	shm_atime;		/* last attach time */
	time_t	shm_dtime;		/* last detach time */
	time_t	shm_ctime;		/* last change time */
	unsigned short	shm_cpid;	/* pid of creator */
	unsigned short	shm_lpid;	/* pid of last operator */
	short	shm_nattch;		/* no. of current attaches */
};
.fi
.in -0.5i
.PP
.in +0.5i
.nf
struct ipc_perm
{
  key_t  key;
  ushort uid;   /* owner euid and egid */
  ushort gid;
  ushort cuid;  /* creator euid and egid */
  ushort cgid;
  ushort mode;  /* lower 9 bits of \fIshmflg\fP */
  ushort seq;   /* sequence number */
};
.fi
.PP
ˡˡ
ΥƥࡦϥƥζͭꡦȤΥǡ¤
.B shmid_ds
ʲΤ褦˽롣
.IP
.B shm_perm.cuid

.B shm_perm.uid
ˤϸƤӽФץμ¸(effective)桼ID ꤵ롣
.IP
.B shm_perm.cgid

.B shm_perm.gid
ˤϸƤӽФץμ¸(effective)롼ID ꤵ롣
.IP
.B shm_perm.mode
β 9ӥåȤˤ
.IR shmflg
β 9ӥåȤꤵ롣
.IP
.B shm_segsz
ˤ
.IR size
ͤꤵ롣
.IP
.BR shm_lpid ,
.BR shm_nattch ,
.B shm_atime

.B shm_dtime
ˤ
.BR 0
ꤵ롣
.IP
.B shm_ctime
ˤϸ߻郎ꤵ롣
.PP
˶ͭꡦȤ¸ߤϡĤǧ졢
줬˲ޡ򤵤Ƥʤå롣
.PP
.SH ƥࡦ
.TP
.B fork()
.B fork()
θˡҥץղ(attach)줿ͭꡦȤѾ롣
.TP
.B exec()
.B exec()
θˡ
Ƥղä줿ͭꡦȤʬΥ(detach)롣
(˲Ϥʤ)
.TP
.B exit()
.B exit()
ˤơ
Ƥղä줿ͭꡦȤʬΥ롣(˲Ϥʤ)
.PP
.SH ֤
ͭʥȼ̻(identifier)
.IR shmid 
֤顼ξ \-1 ֤
.SH 顼
Ԥ
.B errno
ʲΤɤ줫ꤵ:
.TP 12
.B EINVAL
\fBSHMMIN\fP > \fIsize\fP  \fIsize\fP > \fBSHMMAX\fP 
\fIsize\fP ȤΥ礭֤롣
.TP
.B EEXIST

.B IPC_CREAT | IPC_EXCL
ꤵƤꡢȤ¸ߤ֤롣
.TP
.B EIDRM
ϥȤ˲(destroy)ޡ˺Ƥ֤롣
.TP
.B ENOSPC
Ƥβǽʶͭ ID
.BR "" ( SHMMNI )
Ȥ̤Ƥ䡢׵ᤵ줿
.I size
ΥȤγƤ
ƥΤζͭ
.BR "" ( SHMALL )
ĶƤ֤롣
.TP
.B ENOENT
Ϳ줿 \fIkey\fP б륻Ȥ¸ߤ
.B IPC_CREAT
ꤵƤʤ֤롣
.TP
.B EACCES
ϥ桼ζͭꡦȤ˥Ĥʤ
֤롣
.TP
.B ENOMEM
ȤκκѤΤΥƤ뤳ȤǤ
ä֤롣
.SH 
.B IPC_PRIVATE
ϥե饰ǤϤʤ
.B key_t
μǤ롣
̤ͤ
.IR key 
˻Ѥ줿ϡƥࡦ
.I shmflg
β 9ӥåȤƤ̵뤷
()ͭꡦȤ롣
.PP
ʲ
.B shmget
˱ƶ붦ͭꡦȻ񸻤¤Ǥ:
.TP 11
.B SHMALL
ƥΤζͭꡦڡκ: ˰¸
.TP
.B SHMMAX
ͭꡦȤΥХñ̤礭ξ: ¸
(ߤ 4M)
.TP
.B SHMMIN
ͭꡦȤΥХñ̤礭β: ¸
(ߤ 1ХȤ¸ŪʺǾ
.B PAGE_SIZE
Ǥ롣)
.TP
.B SHMMNI
ƥΤζͭ꡼οξ: ¸(ߤ 4096)
.PP
μǤϥץζͭꡦȤ
Ѥξ
.RB ( SHMSEG )
¸ߤʤ
.SH Х 
.B IPC_PRIVATE
ѤȤƤ⡢Ƥ줿ͭꡦȤ
¾Υץ뤳Ȥ˸뤳ȤϤǤʤ
.PP
եƱͤˡΤȤץζͭꡦȤؤ
¾Ūʥݾڤͭˡ¸ߤʤ
.B IPC_CREAT

.B IPC_EXCL
ξ
.I shmflg
ꤹ뤳Ȥ()
ͭꡦȤ뤳ȤΤߤݾڤ
ΥȤؤ¾ŪʥݾڤΤǤϤʤ
.SH 
SVr4, SVID.  SVr4 ˤ¾ EEXIST 顼֤εҤ롣
SVr4  SVID ˤ EIDRM ˤĤƤεҤϤʤ
.SH Ϣ
.BR ftok (3),
.BR ipc (5),
.BR shmctl (2),
.BR shmat (2),
.BR shmdt (2)