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
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.
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 <balasub [AT] cis.edu>
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 at <https://github.com/util-linux/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/>;.