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

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
           Print 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.

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

       -b, --bytes
           Print the sizes in bytes rather than in a human-readable

           By default, the unit, sizes are expressed in, is byte, and
           unit prefixes are in power of 2^10 (1024). Abbreviations of
           symbols are exhibited truncated in order to reach a better
           readability, by exhibiting alone the first letter of them;
           examples: "1 KiB" and "1 MiB" are respectively exhibited as
           "1 K" and "1 M", then omitting on purpose the mention "iB",
           which is part of these abbreviations.

           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 at

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
       2024-06-14. (At that time, the date of the most recent commit
       that was found in the repository was 2024-06-10.) 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 2.39.594-1e0ad      2023-07-19                        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)