The ipcs Command
Keywords: lpg

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### The `ipcs` Command

The `ipcs` command can be used to obtain the status of all System V IPC objects. The Linux version of this tool was also authored by Krishna Balasubramanian.

    ipcs     -q:    Show only message queues
    ipcs     -s:    Show only semaphores
    ipcs     -m:    Show only shared memory
    ipcs --help:    Additional arguments

By default, all three categories of objects are shown. Consider the following sample output of `ipcs`:

    ------ Shared Memory Segments --------
    shmid     owner     perms     bytes     nattch    status

    ------ Semaphore Arrays --------
    semid     owner     perms     nsems     status

    ------ Message Queues --------
    msqid     owner     perms     used-bytes  messages
    0         root      660       5           1

Here we see a single message queue which has an identifier of ``0''. It is owned by the user root, and has octal permissions of `660`, or `-rw-rw--`. There is one message in the queue, and that message has a total size of 5 bytes.

The `ipcs` command is a very powerful tool which provides a peek into the kernel's storage mechanisms for IPC objects. Learn it, use it, revere it.