使用ipcs命令，不加如何参数时，会把共享内存、信号量、消息队列的信息都打印出来，如果只想显示共享内存信息，使用如下命令：
[root@dbserver ~]# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x6c6c6536 0 root 600 4096 0
0x00000000 131073 root 600 393216 2 dest
0x00000000 163842 root 600 393216 2 dest
0x00000000 196611 root 600 393216 2 dest
0x00000000 229380 root 600 393216 2 dest
0x00000000 262149 root 600 393216 2 dest
0x00000000 294918 root 600 393216 2 dest
0x00000000 327687 root 600 393216 2 dest
0x00000000 360456 root 600 393216 2 dest
0x00000000 393225 root 600 393216 2 dest
0x00000000 425994 root 600 393216 2 dest
0x00000000 458763 root 600 393216 2 dest
0x00000000 491532 root 600 393216 2 dest
0x00000000 851981 oracle 640 4096 0
0x00000000 884750 oracle 640 4096 0
0x29f7a5c4 917519 oracle 640 4096 0
0x00000000 655376 root 600 393216 2 dest
0x00000000 688145 root 600 393216 2 dest
0x00000000 720914 root 600 393216 2 dest
0x00000000 753683 root 600 393216 2 dest
0x00000000 786452 root 600 393216 2 dest
ipcs的帮助手册
[root@dbserver ~]# man ipcs
IPCS(1) Linux Programmer’s Manual IPCS(1)
NAME
ipcs - provide information on ipc facilities
SYNOPSIS
ipcs [-asmq] [-tclup]
ipcs [-smq] -i id
ipcs -h
DESCRIPTION
ipcs provides information on the ipc facilities for which the calling process has read access.
The -i option allows a specific resource id to be specified. Only information on this id will be printed.
Resources may be specified as follows:
-m shared memory segments
-q message queues
-s semaphore arrays
-a all (this is the default)
The output format may be specified as follows:
-t time
-p pid
-c creator
-l limits
-u summary
SEE ALSO
ipcrm(1), ipcmk(1)
CONFORMING TO
The Linux ipcs utility is not fully compatible to the POSIX ipcs utility. The Linux version does not support
the -b and -o options, but does support the -l and -u options not defined by POSIX. The portable application
shall not use the -a, -b, -o, -l, and -u options.
AUTHOR
krishna balasubramanian (balasub@cis.ohio-state.edu)
AVAILABILITY
The ipcs command is part of the util-linux-ng package and is available from ftp://ftp.ker-
nel.org/pub/linux/utils/util-linux-ng/.
Linux 0.99 9 October 1993 IPCS(1)
使用举例：
[root@dbserver ~]# ipcs -sa
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x6c6c6536 0 root 600 4096 0
0x00000000 131073 root 600 393216 2 dest
0x00000000 163842 root 600 393216 2 dest
0x00000000 196611 root 600 393216 2 dest
0x00000000 229380 root 600 393216 2 dest
0x00000000 262149 root 600 393216 2 dest
0x00000000 294918 root 600 393216 2 dest
0x00000000 327687 root 600 393216 2 dest
0x00000000 360456 root 600 393216 2 dest
0x00000000 393225 root 600 393216 2 dest
0x00000000 425994 root 600 393216 2 dest
0x00000000 458763 root 600 393216 2 dest
0x00000000 491532 root 600 393216 2 dest
0x00000000 851981 oracle 640 4096 0
0x00000000 884750 oracle 640 4096 0
0x29f7a5c4 917519 oracle 640 4096 0
0x00000000 655376 root 600 393216 2 dest
0x00000000 688145 root 600 393216 2 dest
0x00000000 720914 root 600 393216 2 dest
0x00000000 753683 root 600 393216 2 dest
0x00000000 786452 root 600 393216 2 dest
------ Semaphore Arrays --------
key semid owner perms nsems
0x00000000 0 root 600 1
0x00000000 65537 root 600 1
0x7f51ec7c 360450 oracle 640 154
------ Message Queues --------
key msqid owner perms used-bytes messages
参数含义：
key: 共享内存的key
shmid：表示共享内存段id
owner：表示共享内存段属于哪个用户
perms:需要注意的是默认情况下600表示除root用户外不允许其他用户查看
bytes：表示共享内存段大小
nattch：表示连接到共享内存段的进程数
status：表示共享内存段的状态，dest表示该内存段被标记为destroyed状态。 其中显示“dest”表示共享内存段已经被删除，但是还有用户在使用它，当该段内存的mode字段设置为SHM_DEST时就会显示“dest”。当用户调用shmctl的IPC_RMID时，内存先查看多少个进程与这个内存关联着，如果关联数为0，就会销毁这段共享内存，否者设置这段内存的mod的mode位为SHM_DEST，如果所有进程都不用则删除这段共享内存。
