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ipcs(1)
NAME
ipcs - Reports Interprocess Communication (IPC) facility status
SYNOPSIS
ipcs [-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 standards
as follows:
ipcs: XCU5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
OPTIONS
-a Same as specifying the -b, -c, -o, -p, and -t options.
-b Writes the maximum number of bytes in message queues, the size of
segments for shared memory, and the number of semaphores in each
semaphore set.
-c Writes the username and group name of the user that made the facility.
-C corefile
Writes report based on contents of file corefile instead of /dev/kmem.
-m Writes information about active shared memory segments.
-N namelist
Writes report based on contents of file namelist instead of /vmunix.
-o 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
-p 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
-q Writes information about active message queues.
-s Writes information about active semaphore set.
-t 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.
T (all)
Type of facility:
q Message queue
m Shared memory segment
s Semaphore
ID (all)
The identifier for the facility entry.
KEY (all)
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.
MODE (all)
The facility access modes and flags. The mode consists of 11 characters
that are interpreted as follows:
The first two characters can be:
L [Tru64 UNIX] If the associated shared memory segment was locked.
R If a process is waiting on a msgrcv() system call.
S If a process is waiting on a msgsnd() system call.
D 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:
r Read permission is granted.
w Write permission is granted.
a Alter permission is granted.
- The indicated permission is not granted.
OWNER (all)
The username of the owner of the facility entry.
GROUP (all)
The name of the group that owns the facility entry.
CREATOR (a,c)
The username of the creator of the facility entry.
CGROUP (a,c)
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.
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 messages outstanding on the
associated message queue.
LSPID (a,p)
The ID of the last process that sent a message to the associated queue.
LRPID (a,p)
The ID of the last process that received a message from the associated
queue.
STIME (a,t)
The time when the last message was sent to the associated queue.
RTIME (a,t)
The time when 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 segment.
CPID (a,p)
The process ID of the creator of the shared memory entry.
LPID (a,p)
The process ID of the last process to attach or detach the shared
memory segment.
ATIME (a,t)
The time when the last attach was completed to the associated shared
memory segment.
DTIME (a,t)
The time when the last detach was completed on the associated shared
memory segment.
NSEMS (a,b)
The number of semaphores in the set associated with the semaphore
entry.
OTIME (a,t)
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
/etc/passwd
Contains user information.
/etc/group
Contains group information.
SEE ALSO
Commands: ipcrm(1)
Functions: msgrcv(2), msgsnd(2), semop(2), shmat(2), shmdt(2)
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