ipcs(1) — Linux manual page

IPCS(1)                       User Commands                       IPCS(1)

NAME         top

       ipcs - show information on IPC facilities

SYNOPSIS         top

       ipcs [options]

DESCRIPTION         top

       ipcs shows information on System V inter-process communication
       facilities. By default it shows information about all three
       resources: shared memory segments, message queues, and semaphore
       arrays.

OPTIONS         top

       -i, --id id
           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.

       -h, --help
           Display help text and exit.

       -V, --version
           Display version and exit.

   Resource options
       -m, --shmems
           Write information about active shared memory segments.

       -q, --queues
           Write information about active message queues.

       -s, --semaphores
           Write information about active semaphore sets.

       -a, --all
           Write information about all three resources (default).

   Output formats
       Of these options only one takes effect: the last one specified.

       -c, --creator
           Show creator and owner.

       -l, --limits
           Show resource limits.

       -p, --pid
           Show PIDs of creator and last operator.

       -t, --time
           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.

       -u, --summary
           Show status summary.

   Representation
       These affect only the -l (--limits) option.

       -b, --bytes
           Print sizes in bytes rather than in human-readable form.

           By default, sizes are shown in units that are powers of 1024
           bytes. The formal abbreviations for these units (KiB, MiB,
           GiB, ...) are further shortened to just their first letter: K,
           M, G, ....

       --human
           Print sizes in human-readable format.

CONFORMING TO         top

       The Linux ipcs utility is not fully compatible to the POSIX ipcs
       utility. The Linux version does not support the POSIX -a, -b and
       -o options, but does support the -l and -u options not defined by
       POSIX. A portable application shall not use the -a, -b, -o, -l,
       and -u options.

NOTES         top

       The current implementation of ipcs obtains information about
       available IPC resources by parsing the files in /proc/sysvipc.
       Before util-linux version v2.23, an alternate mechanism was used:
       the IPC_STAT command of msgctl(2), semctl(2), and shmctl(2). This
       mechanism is also used in later util-linux versions in the case
       where /proc is unavailable. A limitation of the IPC_STAT mechanism
       is that it can only be used to retrieve information about IPC
       resources for which the user has read permission.

AUTHORS         top

       Krishna Balasubramanian <balasub@cis.ohio-state.edu>

SEE ALSO         top

       ipcmk(1), ipcrm(1), msgrcv(2), msgsnd(2), semget(2), semop(2),
       shmat(2), shmdt(2), shmget(2), sysvipc(7)

REPORTING BUGS         top

       For bug reports, use the issue tracker
       <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY         top

       The ipcs command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>. This page is
       part of the util-linux (a random collection of Linux utilities)
       project. Information about the project can be found at 
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a
       bug report for this manual page, send it to
       util-linux@vger.kernel.org. This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2025-08-11. (At that time, the date of the most recent commit that
       was found in the repository was 2025-08-05.) If you discover any
       rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a
       mail to man-pages@man7.org

util-linux 2.42-start-521-ec46  2025-08-09                        IPCS(1)

Pages that refer to this page: ipcmk(1),  ipcrm(1),  lsipc(1),  msgctl(2),  semctl(2),  semget(2),  shmctl(2),  proc_sysvipc(5),  sysvipc(7)

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