Manual: ipcs

IPCS(1)							User Commands						     IPCS(1)

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 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 the sizes in bytes rather than in a human-readable format.

	   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.

       --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),
       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
       Krishna Balasubramanian 

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

REPORTING BUGS
       For bug reports, use the issue tracker .

AVAILABILITY
       The ipcs command is part of the util-linux package which can be downloaded from Linux Kernel Archive
       .

util-linux 2.41.3					 2025-12-15						     IPCS(1)