# phpman > man > ipcs(1)

> **TLDR:** Show information about the usage of XSI IPC facilities: shared memory segments, message queues, and semaphore arrays.
>
- Show information about [a]ll the IPC:
  `ipcs -a`
- Show information about active shared [m]emory segments, message [q]ueues or [s]empahore sets:
  `ipcs {{m|-q|-s}}`
- Show information on maximum allowable size in [b]ytes:
  `ipcs -b`
- Show [c]reator's user name and group name for all IPC facilities:
  `ipcs -c`
- Show the [p]ID of the last operators for all IPC facilities:
  `ipcs -p`
- Show access [t]imes for all IPC facilities:
  `ipcs -t`
- Show [o]utstanding usage for active message queues, and shared memory segments:
  `ipcs -o`

*Source: tldr-pages*

---

[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
           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)