ipcs(1) User Commands ipcs(1)
ipcs - report inter-process communication facilities status
ipcs [ -abcmopqst ] [ -C corefile ] [ -N namelist ]
ipcs prints information about active inter-process communi-
cation facilities. Without options, information is printed
in short format for message queues, shared memory, and sema-
phores that are currently active in the system.
The information that is displayed is controlled by the
-m Print information about active shared memory
-q Print information about active message
-s Print information about active semaphores.
If -q, -m, or -s are specified, information about only those
indicated is printed. If none of these three are specified,
information about all three is printed subject to these
-a Use all print options. (This is a shorthand
notation for -b, -c, -o, -p, and -t.)
-b Print information on biggest allowable size:
maximum number of bytes in messages on queue
for message queues, size of segments for
shared memory, and number of semaphores in
each set for semaphores. See below for mean-
ing of columns in a listing.
-c Print creator's login name and group name.
-o Print information on outstanding usage:
number of messages on queue and total number
of bytes in messages on queue for message
queues and number of processes attached to
shared memory segments.
-p Print process number information: process ID
of last process to send a message, process ID
of last process to receive a message on mes-
sage queues, process ID of creating process,
and process ID of last process to attach or
detach on shared memory segments. See below.
-t Print time information: time of the last
control operation that changed the access
permissions for all facilities, time of last
msgsnd and last msgrcv on message queues,
time of last shmat and last shmdt on shared
memory, time of last semop on semaphores.
-C corefile Use the file corefile in place of ⁄dev⁄mem
and ⁄dev⁄kmem. Use a core dump obtained from
savecore(1M) in place of ⁄dev⁄mem and
⁄dev⁄kmem. Without the -C option (default),
the running system image is used.
-N namelist Use the file namelist in place of ⁄dev⁄ksyms.
The column headings and the meaning of the columns in an
ipcs listing are given below; the letters in parentheses
indicate the options that cause the corresponding heading to
appear; "all" means that the heading always appears. Note:
These options only determine what information is provided
for each facility; they do not determine which facilities
T (all) Type of the facility:
q message queue
m shared memory segment
ID (all) The identifier for the facility entry.
KEY (all) The key used as an argument to msgget,
semget, or shmget to create the facility
entry. (Note: The key of a shared memory
segment is changed to IPC_PRIVATE when the
segment has been removed until all processes
attached to the segment detach it.)
MODE (all) The facility access modes and flags: The
mode consists of 11 characters that are
interpreted as follows. The first two char-
R A process is waiting on a msgrcv.
S A process is waiting on a msgsnd.
D The associated shared memory segment
has been removed. It will disappear
when the last process attached to
the segment detaches it.
C The associated shared memory segment
is to be cleared when the first
attach is executed.
- The corresponding special flag is
The next nine characters are interpreted as
three sets of three bits each. The first
set refers to the owner's permissions; the
next to permissions of others in the user-
group of the facility entry; and the last to
all others. Within each set, the first
character indicates permission to read, the
second character indicates permission to
write or alter the facility entry, and the
last character is currently unused.
The permissions are indicated as follows:
r Read permission is granted.
w Write permission is granted.
a Alter permission is granted.
- The indicated permission is not
OWNER (all) The login name of the owner of the facility
GROUP (all) The group name of the group of the owner of
the facility entry.
CREATOR (a,c) The login name of the creator of the facil-
CGROUP (a,c) The group name of the group of the creator
of the facility entry.
CBYTES (a,o) The number of bytes in messages currently
outstanding on the associated message queue.
QNUM (a,o) The number of messages currently outstanding
on the associated message queue.
QBYTES (a,b) The maximum number of bytes allowed in mes-
sages outstanding on the associated message
LSPID (a,p) The process ID of the last process to send a
message to the associated queue.
LRPID (a,p) The process ID of the last process to
receive a message from the associated queue.
STIME (a,t) The time the last message was sent to the
RTIME (a,t) The time the last message was received from
the associated queue.
CTIME (a,t) The time when the associated entry was
created or changed.
NATTCH (a,o) The number of processes attached to the
associated shared memory segment.
SEGSZ (a,b) The size of the associated shared memory
CPID (a,p) The process ID of the creator of the shared
LPID (a,p) The process ID of the last process to attach
or detach the shared memory segment.
ATIME (a,t) The time the last attach was completed to
the associated shared memory segment.
DTIME (a,t) The time the last detach was completed on
the associated shared memory segment.
NSEMS (a,b) The number of semaphores in the set associ-
ated with the semaphore entry.
OTIME (a,t) The time the last semaphore operation was
completed on the set associated with the
⁄etc⁄group group names
⁄etc⁄passwd user names
⁄dev⁄ksyms system namelist
msgop(2), semop(2), shmop(2)
If the user specifies either the -C or -N flag, the real and
effective UID⁄GID is set to the real UID⁄GID of the user
Things can change while ipcs is running; the information it
gives is guaranteed to be accurate only when it was
SunOS 5.5.1 Last change: 2 Feb 1994 5