IPCS(1) User Commands IPCS(1)
NAME
ipcs - show information on IPC facilities
SYNOPSIS
ipcs [options]
DESCRIPTION
ipcs shows information on 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 re-
source 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) 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.
--human
Print sizes in human-readable format.
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 re-
trieve information about IPC resources for which the user has read per-
mission.
SEE ALSO
ipcmk(1), ipcrm(1), msgrcv(2), msgsnd(2), semget(2), semop(2),
shmat(2), shmdt(2), shmget(2)
CONFORMING TO
The Linux ipcs utility is not fully compatible to the POSIX ipcs util-
ity. The Linux version does not support the POSIX -a, -b and -o op-
tions, 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.
AUTHOR
Krishna Balasubramanian <balasub@cis.ohio-state.edu>
AVAILABILITY
The ipcs command is part of the util-linux package and is available
from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-
linux/>.
util-linux July 2014 IPCS(1)