IPCS(1) BSD General Commands Manual IPCS(1)NAMEipcs — report System V interprocess communication facilities status
SYNOPSISipcs [-abcmopqstMQSTy] [-C core] [-N system] [-u user]
The ipcs utility provides information on System V interprocess communica‐
tion (IPC) facilities on the system.
The options are as follows:
-a Show the maximum amount of information possible when displaying
active semaphores, message queues, and shared memory segments.
(This is shorthand for specifying the -b, -c, -o, -p, and -t
-b Show the maximum allowed sizes for active semaphores, message
queues, and shared memory segments. The “maximum allowed size”
is the maximum number of bytes in a message on a message queue,
the size of a shared memory segment, or the number of semaphores
in a set of semaphores.
-c Show the creator's name and group for active semaphores, message
queues, and shared memory segments.
-m Display information about active shared memory segments.
-o Show outstanding usage for active message queues, and shared mem‐
ory segments. The “outstanding usage” is the number of messages
in a message queue, or the number of processes attached to a
shared memory segment.
-p Show the process ID information for active semaphores, message
queues, and shared memory segments. The “process ID information”
is the last process to send a message to or receive a message
from a message queue, the process that created a semaphore, or
the last process to attach or detach a shared memory segment.
-q Display information about active message queues.
-s Display information about active semaphores.
-t Show access times for active semaphores, message queues, and
shared memory segments. The access times is the time of the last
control operation on an IPC object, the last send or receive of a
message, the last attach or detach of a shared memory segment, or
the last operation on a semaphore.
Extract values associated with the name list from the specified
core instead of the default /dev/kmem. Implies -y.
-M Display system information about shared memory.
Extract the name list from the specified system instead of the
default /boot/kernel/kernel. Implies -y.
-Q Display system information about messages queues.
-S Display system information about semaphores.
-T Display system information about shared memory, message queues
-y Use the kvm(3) interface instead of the sysctl(3) interface to
extract the required information. If ipcs is to operate on the
running system, using kvm(3) will require read privileges to
Display information about IPC mechanisms owned by user. User
specification can be in the form of a numeric UID or a login
If none of the -M, -m, -Q, -q, -S, or -s options are specified, informa‐
tion about all active IPC facilities is listed.
System data structures may change while ipcs is running; the output of
ipcs is not guaranteed to be consistent.
/dev/kmem default kernel memory
/boot/kernel/kernel default system name list
Thorsten Lockert ⟨firstname.lastname@example.org⟩
This manual page is woefully incomplete, because it does not at all
attempt to explain the information printed by ipcs.
BSD March 24, 2004 BSD