{
    "mode": "man",
    "parameter": "ipcs",
    "section": "1",
    "url": "https://www.chedong.com/phpMan.php/man/ipcs/1/json",
    "generated": "2026-06-13T13:52:29Z",
    "synopsis": "ipcs [options]",
    "sections": {
        "NAME": {
            "content": "ipcs - show information on IPC facilities\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "ipcs [options]\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "ipcs shows information on System V inter-process communication facilities. By default it\nshows information about all three resources: shared memory segments, message queues, and\nsemaphore arrays.\n",
            "subsections": []
        },
        "OPTIONS": {
            "content": "",
            "subsections": [
                {
                    "name": "-i --id",
                    "content": "Show full details on just the one resource element identified by id. This option needs to\nbe combined with one of the three resource options: -m, -q or -s.\n",
                    "flag": "-i",
                    "long": "--id"
                },
                {
                    "name": "-h --help",
                    "content": "Display help text and exit.\n",
                    "flag": "-h",
                    "long": "--help"
                },
                {
                    "name": "-V --version",
                    "content": "Display version information and exit.\n",
                    "flag": "-V",
                    "long": "--version"
                },
                {
                    "name": "Resource options",
                    "content": ""
                },
                {
                    "name": "-m --shmems",
                    "content": "Write information about active shared memory segments.\n",
                    "flag": "-m",
                    "long": "--shmems"
                },
                {
                    "name": "-q --queues",
                    "content": "Write information about active message queues.\n",
                    "flag": "-q",
                    "long": "--queues"
                },
                {
                    "name": "-s --semaphores",
                    "content": "Write information about active semaphore sets.\n",
                    "flag": "-s",
                    "long": "--semaphores"
                },
                {
                    "name": "-a --all",
                    "content": "Write information about all three resources (default).\n",
                    "flag": "-a",
                    "long": "--all"
                },
                {
                    "name": "Output formats",
                    "content": "Of these options only one takes effect: the last one specified.\n"
                },
                {
                    "name": "-c --creator",
                    "content": "Show creator and owner.\n",
                    "flag": "-c",
                    "long": "--creator"
                },
                {
                    "name": "-l --limits",
                    "content": "Show resource limits.\n",
                    "flag": "-l",
                    "long": "--limits"
                },
                {
                    "name": "-p --pid",
                    "content": "Show PIDs of creator and last operator.\n",
                    "flag": "-p",
                    "long": "--pid"
                },
                {
                    "name": "-t --time",
                    "content": "Write time information. The time of the last control operation that changed the access\npermissions for all facilities, the time of the last msgsnd(2) and msgrcv(2) operations\non message queues, the time of the last shmat(2) and shmdt(2) operations on shared\nmemory, and the time of the last semop(2) operation on semaphores.\n",
                    "flag": "-t",
                    "long": "--time"
                },
                {
                    "name": "-u --summary",
                    "content": "Show status summary.\n",
                    "flag": "-u",
                    "long": "--summary"
                },
                {
                    "name": "Representation",
                    "content": "These affect only the -l (--limits) option.\n"
                },
                {
                    "name": "-b --bytes",
                    "content": "Print sizes in bytes.\n",
                    "flag": "-b",
                    "long": "--bytes"
                },
                {
                    "name": "--human",
                    "content": "Print sizes in human-readable format.\n",
                    "long": "--human"
                }
            ]
        },
        "CONFORMING TO": {
            "content": "The Linux ipcs utility is not fully compatible to the POSIX ipcs utility. The Linux version\ndoes not support the POSIX -a, -b and -o options, but does support the -l and -u options not\ndefined by POSIX. A portable application shall not use the -a, -b, -o, -l, and -u options.\n",
            "subsections": []
        },
        "NOTES": {
            "content": "The current implementation of ipcs obtains information about available IPC resources by\nparsing the files in /proc/sysvipc. Before util-linux version v2.23, an alternate mechanism\nwas used: the IPCSTAT command of msgctl(2), semctl(2), and shmctl(2). This mechanism is also\nused in later util-linux versions in the case where /proc is unavailable. A limitation of the\nIPCSTAT mechanism is that it can only be used to retrieve information about IPC resources\nfor which the user has read permission.\n",
            "subsections": []
        },
        "AUTHORS": {
            "content": "Krishna Balasubramanian <balasub@cis.ohio-state.edu>\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "ipcmk(1), ipcrm(1), msgrcv(2), msgsnd(2), semget(2), semop(2), shmat(2), shmdt(2), shmget(2),\nsysvipc(7)\n",
            "subsections": []
        },
        "REPORTING BUGS": {
            "content": "For bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.\n",
            "subsections": []
        },
        "AVAILABILITY": {
            "content": "The ipcs command is part of the util-linux package which can be downloaded from Linux Kernel\nArchive <https://www.kernel.org/pub/linux/utils/util-linux/>.\n\n\n\nutil-linux 2.37.2                            2021-06-02                                      IPCS(1)",
            "subsections": []
        }
    },
    "summary": "ipcs - show information on IPC facilities",
    "flags": [
        {
            "flag": "-i",
            "long": "--id",
            "arg": null,
            "description": "Show full details on just the one resource element identified by id. This option needs to be combined with one of the three resource options: -m, -q or -s."
        },
        {
            "flag": "-h",
            "long": "--help",
            "arg": null,
            "description": "Display help text and exit."
        },
        {
            "flag": "-V",
            "long": "--version",
            "arg": null,
            "description": "Display version information and exit."
        },
        {
            "flag": "-m",
            "long": "--shmems",
            "arg": null,
            "description": "Write information about active shared memory segments."
        },
        {
            "flag": "-q",
            "long": "--queues",
            "arg": null,
            "description": "Write information about active message queues."
        },
        {
            "flag": "-s",
            "long": "--semaphores",
            "arg": null,
            "description": "Write information about active semaphore sets."
        },
        {
            "flag": "-a",
            "long": "--all",
            "arg": null,
            "description": "Write information about all three resources (default)."
        },
        {
            "flag": "-c",
            "long": "--creator",
            "arg": null,
            "description": "Show creator and owner."
        },
        {
            "flag": "-l",
            "long": "--limits",
            "arg": null,
            "description": "Show resource limits."
        },
        {
            "flag": "-p",
            "long": "--pid",
            "arg": null,
            "description": "Show PIDs of creator and last operator."
        },
        {
            "flag": "-t",
            "long": "--time",
            "arg": null,
            "description": "Write time information. The time of the last control operation that changed the access permissions for all facilities, the time of the last msgsnd(2) and msgrcv(2) operations on message queues, the time of the last shmat(2) and shmdt(2) operations on shared memory, and the time of the last semop(2) operation on semaphores."
        },
        {
            "flag": "-u",
            "long": "--summary",
            "arg": null,
            "description": "Show status summary."
        },
        {
            "flag": "-b",
            "long": "--bytes",
            "arg": null,
            "description": "Print sizes in bytes."
        },
        {
            "flag": "",
            "long": "--human",
            "arg": null,
            "description": "Print sizes in human-readable format."
        }
    ],
    "examples": [],
    "see_also": [
        {
            "name": "ipcmk",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/ipcmk/1/json"
        },
        {
            "name": "ipcrm",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/ipcrm/1/json"
        },
        {
            "name": "msgrcv",
            "section": "2",
            "url": "https://www.chedong.com/phpMan.php/man/msgrcv/2/json"
        },
        {
            "name": "msgsnd",
            "section": "2",
            "url": "https://www.chedong.com/phpMan.php/man/msgsnd/2/json"
        },
        {
            "name": "semget",
            "section": "2",
            "url": "https://www.chedong.com/phpMan.php/man/semget/2/json"
        },
        {
            "name": "semop",
            "section": "2",
            "url": "https://www.chedong.com/phpMan.php/man/semop/2/json"
        },
        {
            "name": "shmat",
            "section": "2",
            "url": "https://www.chedong.com/phpMan.php/man/shmat/2/json"
        },
        {
            "name": "shmdt",
            "section": "2",
            "url": "https://www.chedong.com/phpMan.php/man/shmdt/2/json"
        },
        {
            "name": "shmget",
            "section": "2",
            "url": "https://www.chedong.com/phpMan.php/man/shmget/2/json"
        },
        {
            "name": "sysvipc",
            "section": "7",
            "url": "https://www.chedong.com/phpMan.php/man/sysvipc/7/json"
        }
    ],
    "tldr": {
        "source": "official",
        "description": "Show information about the usage of XSI IPC facilities: shared memory segments, message queues, and semaphore arrays.",
        "examples": [
            {
                "description": "Show information about [a]ll the IPC",
                "command": "ipcs -a"
            },
            {
                "description": "Show information about active shared [m]emory segments, message [q]ueues or [s]empahore sets",
                "command": "ipcs {{m|-q|-s}}"
            },
            {
                "description": "Show information on maximum allowable size in [b]ytes",
                "command": "ipcs -b"
            },
            {
                "description": "Show [c]reator's user name and group name for all IPC facilities",
                "command": "ipcs -c"
            },
            {
                "description": "Show the [p]ID of the last operators for all IPC facilities",
                "command": "ipcs -p"
            },
            {
                "description": "Show access [t]imes for all IPC facilities",
                "command": "ipcs -t"
            },
            {
                "description": "Show [o]utstanding usage for active message queues, and shared memory segments",
                "command": "ipcs -o"
            }
        ]
    }
}