# ipcs

## 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 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



           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.
    


## 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/>. 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)
    


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