Provided by: util-linux_2.38.1-4ubuntu1_amd64 bug


       ipcs - show information on IPC facilities


       ipcs [options]


       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.


       -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 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.

           Print sizes in human-readable format.


       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.


       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.


       Krishna Balasubramanian <>


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


       For bug reports, use the issue tracker at


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