Linux操作系統ipcs命令
ipcs: 主要提供調用進程讀取訪問一些ipc設備信息.如:共享內存,信號量,消息隊列
ipcs [ -asmq ] [ -tclup ]
ipcs [ -smq ] -i id
-m 輸出共享內存(shared memory segments)的信息
-s 輸出信號量(semaphore)的信息
-q 輸出消息隊列(message queues)的信息
-l limits
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[email protected]:log# ipcs
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------ Shared Memory Segments --------
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key shmid owner perms bytes nattch status
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------ Semaphore Arrays --------
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key semid owner perms nsems
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0x00002af9 131072 db 664 1
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0x00002afb 163841 db 664 1
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0x00002b03 65538 db 664 1
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0x00002b05 98307 db 664 1
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------ Message Queues --------
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key msqid owner perms used-bytes messages
其中Key為應用程序存取資源使用的參數,id為資源條目的唯一標示號.
例如實際情況可能會遇到db用戶程序是用root賬戶啟動,這時首先root賬戶關掉db用戶的程序,但共享內存有可能未釋放,需要手動刪除.這就要用到ipcrm 命令.
ipcrm - remove a message queue, semaphore set or shared memory id
ipcrm [ -M key | -m id | -Q key | -q id | -S key | -s id ]
-m shmid
-q msqid
-s semid
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[email protected]:log# ipcs -s
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------ Semaphore Arrays --------
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key semid owner perms nsems
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0x00002af9 131072 db 664 1
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0x00002afb 163841 db 664 1
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0x00002b03 65538 db 664 1
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0x00002b05 98307 db 664 1
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[email protected]:log# ipcrm -s 131072
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[email protected]:log# ipcrm -s 163841
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[email protected]:log# ipcrm -s 65538
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[email protected]:log# ipcrm -s 98307
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[email protected]:~# ipcs
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------ Shared Memory Segments --------
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key shmid owner perms bytes nattch status
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------ Semaphore Arrays --------
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key semid owner perms nsems
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------ Message Queues --------
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key msqid owner perms used-bytes messages
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[email protected]:~# ipcs -l
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------ Shared Memory Limits --------
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max number of segments = 4096
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max seg size (kbytes) = 32768
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max total shared memory (kbytes) = 8388608
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min seg size (bytes) = 1
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------ Semaphore Limits --------
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max number of arrays = 128
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max semaphores per array = 250
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max semaphores system wide = 32000
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max ops per semop call = 32
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semaphore max value = 32767
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------ Messages: Limits --------
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max queues system wide = 16
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max size of message (bytes) = 8192
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default max size of queue (bytes) = 16384
有2種方法改變其值
1.更改/etc/sysctl.conf ,添加kernel.msgmni = 1024,生效加載配置使用sysctl -p
kernel.msgmni 該文件指定消息隊列標識的最大數目，即系統范圍內最大多少個消息隊列。
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[email protected]:~# cat /proc/sys/kernel/msgmni
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16
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[email protected]:~# vim /etc/sysctl.conf
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[email protected]:~# sysctl -p
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kernel.msgmni = 1024
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[email protected]:~# cat /proc/sys/kernel/msgmni
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1024
2.在root下使用sysctl命令,直接生效.
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[email protected]:~# sysctl -w kernel.msgmni=16
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kernel.msgmni = 16
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[email protected]:~# cat /proc/sys/kernel/msgmni
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16
