# phpman > info > ipcs

[IPCS(1)](https://www.chedong.com/phpMan.php/man/IPCS/1/markdown)                          User Commands                         [IPCS(1)](https://www.chedong.com/phpMan.php/man/IPCS/1/markdown)

NAME
       ipcs - show information on IPC facilities

SYNOPSIS
       ipcs [options]

DESCRIPTION
       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
       -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 information 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)](https://www.chedong.com/phpMan.php/man/msgsnd/2/markdown) and [msgrcv(2)](https://www.chedong.com/phpMan.php/man/msgrcv/2/markdown) operations on message queues, the time
           of the last [shmat(2)](https://www.chedong.com/phpMan.php/man/shmat/2/markdown) and [shmdt(2)](https://www.chedong.com/phpMan.php/man/shmdt/2/markdown) operations on shared memory, and
           the time of the last [semop(2)](https://www.chedong.com/phpMan.php/man/semop/2/markdown) operation on semaphores.

       -u, --summary
           Show status summary.

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

       -b, --bytes
           Print sizes in bytes.

       --human
           Print sizes in human-readable format.

CONFORMING TO
       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
       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)](https://www.chedong.com/phpMan.php/man/msgctl/2/markdown), [semctl(2)](https://www.chedong.com/phpMan.php/man/semctl/2/markdown), and [shmctl(2)](https://www.chedong.com/phpMan.php/man/shmctl/2/markdown). 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
       Krishna Balasubramanian <<balasub@cis.ohio-state.edu>>

SEE ALSO
       [ipcmk(1)](https://www.chedong.com/phpMan.php/man/ipcmk/1/markdown), [ipcrm(1)](https://www.chedong.com/phpMan.php/man/ipcrm/1/markdown), [msgrcv(2)](https://www.chedong.com/phpMan.php/man/msgrcv/2/markdown), [msgsnd(2)](https://www.chedong.com/phpMan.php/man/msgsnd/2/markdown), [semget(2)](https://www.chedong.com/phpMan.php/man/semget/2/markdown), [semop(2)](https://www.chedong.com/phpMan.php/man/semop/2/markdown),
       [shmat(2)](https://www.chedong.com/phpMan.php/man/shmat/2/markdown), [shmdt(2)](https://www.chedong.com/phpMan.php/man/shmdt/2/markdown), [shmget(2)](https://www.chedong.com/phpMan.php/man/shmget/2/markdown), [sysvipc(7)](https://www.chedong.com/phpMan.php/man/sysvipc/7/markdown)

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

AVAILABILITY
       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/>>.

util-linux 2.37.2                 2021-06-02                           [IPCS(1)](https://www.chedong.com/phpMan.php/man/IPCS/1/markdown)