ipcs(1)ipcs(1)NAMEipcs - Reports Interprocess Communication (IPC) facility status
SYNOPSISipcs [-a | -bcopt] [-mqs] [-C corefile] [-N namelist]
The ipcs command writes to the standard output information about active
Interprocess Communication (IPC) facilities.
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
ipcs: XCU5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
OPTIONS
Same as specifying the -b, -c, -o, -p, and -t options. Writes the max‐
imum number of bytes in message queues, the size of segments for shared
memory, and the number of semaphores in each semaphore set. Writes the
username and group name of the user that made the facility. Writes
report based on contents of file corefile instead of /dev/kmem. Writes
information about active shared memory segments. Writes report based
on contents of file namelist instead of /vmunix. Writes the following
usage information: Number of messages on queue Total number of bytes in
message queues Number of processes attached to shared memory segments
Writes the following: Process number of the last process to receive a
message on message queues Process number of the creating process
Process number of last process to attach or detach on shared memory
segments Writes information about active message queues. Writes infor‐
mation about active semaphore set. Writes the following: Time of the
last control operation that changed the access permissions for all
facilities Time of the last msgsnd() and last msgrcv() on message
queues Time of the last shmat() and last shmdt() on shared memory Time
of the last semop() on semaphore sets
DESCRIPTION
If you do not specify any options, ipcs writes information in a short
form about currently active message queues, shared memory segments,
semaphores, remote queues, and local queue headers.
Column Headings
The column headings and the meaning of the columns in an ipcs listing
follow. The letters in parentheses indicate the flags that cause the
corresponding heading to appear. The word all means that the heading
always appears. The flags only determine what information is provided
for each facility; they do not determine which facilities are listed.
Type of facility: Message queue Shared memory segment Semaphore The
identifier for the facility entry. The key used as a parameter to the
msgget(), semget() or shemget() system calls to make the facility
entry.
Note that the key of a shared memory segment is changed to
IPC_PRIVATE when the segment is removed. This change remains in
effect until all processes attached to the segment detach it.
The facility access modes and flags. The mode consists of 11
characters that are interpreted as follows:
The first two characters can be: [Tru64 UNIX] If the associated
shared memory segment was locked. If a process is waiting on a
msgrcv() system call. If a process is waiting on a msgsnd()
system call. If the associated shared memory segment was
removed. It disappears when the last process attached to the
segment detaches it. If the corresponding special flag is not
set.
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: Read permission is
granted. Write permission is granted. Alter permission is
granted. The indicated permission is not granted. The username
of the owner of the facility entry. The name of the group that
owns the facility entry. The username of the creator of the
facility entry. The group name of the group of the creator of
the facility entry.
Note that for the OWNER, GROUP, CREATOR, and CGROUP, the user
and group IDs display instead of the usernames. The number of
bytes in messages currently outstanding on the associated mes‐
sage queue. The number of messages currently outstanding on the
associated message queue. The maximum number of bytes allowed
in messages outstanding on the associated message queue. The ID
of the last process that sent a message to the associated queue.
The ID of the last process that received a message from the
associated queue. The time when the last message was sent to
the associated queue. The time when the last message was
received from the associated queue. The time when the associ‐
ated entry was created or changed. The number of processes
attached to the associated shared memory segment. The size of
the associated shared memory segment. The process ID of the
creator of the shared memory entry. The process ID of the last
process to attach or detach the shared memory segment. The time
when the last attach was completed to the associated shared mem‐
ory segment. The time when the last detach was completed on the
associated shared memory segment. The number of semaphores in
the set associated with the semaphore entry. The time when the
last semaphore operation was completed on the set associated
with the semaphore entry.
EXAMPLES
Sample output from entering ipcs without options follows.
Message Queues:
T ID KEY MODE OWNER GROUP
q 4 0x41002ab4 --rw------- root system
Shared Memory:
T ID KEY MODE OWNER GROUP
m 0 0x3253bc5c --rw-rw-rw- root system
m 129 0 DLrw------- root daemon
Semaphores:
T ID KEY MODE OWNER GROUP
s 0 0x41002ab4 --ra------- root system
Output is formatted differently if the environment variable CMD_ENV is
set to the string svr4. For example:
IPC status from /dev/kmem as of Thu Mar 26 11:31:03 1998
T ID KEY MODE OWNER GROUP
Message Queues:
q 4 0x41002ab4 --rw------- root system
Shared Memory:
m 0 0x3253bc5c --rw-rw-rw- root system
m 129 0 DLrw------- root daemon
Semaphores:
s 0 0x41002ab4 --ra------- root system
FILES
Contains user information. Contains group information.
SEE ALSO
Commands: ipcrm(1)
Functions: msgrcv(2), msgsnd(2), semop(2), shmat(2), shmdt(2)ipcs(1)