ipcs(1) General Commands Manual ipcs(1)
Name
ipcs - report interprocess communication facilities status
Syntax
ipcs [options]
Description
The command provides information about active, interprocess communication facilities, message queues, shared memory, and semaphores that
are currently active in the system.
Options
The information is displayed in columns and is controlled by the following options:
-m Displays information about active shared memory segments
-q Displays information about active message queues
-s Displays information about active semaphores
If any of the options -q, -m, or -s are specified, information about only those indicated are printed. If none of these three is speci-
fied, information about all three are printed.
-a Uses all print options (shorthand notation for -b, -c, -o, -p and -t)
-b Displays the biggest allowable size information (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)
-C Uses the specified core file (next argument) in place of
-c Displays creator's login name and group name
-N Uses the specified namelist (next argument) in place of
-o Displays the outstanding usage information (number of messages in queue, size of each and number of processes attached to shared
memory segments)
-p Displays the process ID information (process ID of last process to send a message and process ID of last process to receive a mes-
sage on message queues and process ID of creating process and process ID of last process to attach or detach on shared memory seg-
ments)
-t Displays all time statistics (time of the last control operation that changed the access permissions for all facilities, time of
last and last on message queues, last and last on shared memory, last on semaphores)
The column headings and the meaning of the columns in an 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 that these options only determine what informa-
tion 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 an argument to or 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. The first two characters are interpreted as follows:
R If the process is waiting on a
S If a process is waiting on a
D If the associated shared memory segment has been removed. It disappears when the last process attached to the
segment detaches it.
C If the associated shared memory segment is to be clear when the first attach is executed.
- If the corresponding special flag is not set.
The next 9 characters are interpreted as three sets of three bits each. The first set refers to the owner's permis-
sions; 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 write or alter the facility entry, and the last character is cur-
rently unused.
The permissions are indicated as follows:
r If read permission is granted
w If write permission is granted
a If alter permission is granted
- If the indicated permission is not granted
OWNER (all) The login name of the owner of the facility entry.
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 facility entry.
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 messages outstanding on the associated message queue.
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 associated queue.
RTIME (a,t) The time the last message was received from the associated queue.
CTIME (a,t) The time 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 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 associated with the semaphore entry.
OTIME (a,t) The time the last semaphore operation was completed on the set associated with the semaphore entry.
Restrictions
Things can change while is running. The picture it gives is only a close approximation to reality.
Files
/vmunix system namelist
/dev/kmem memory
/etc/passwd user names
/etc/group group names
See Also
ipcrm(2), msgop(2), semop(2), shmop(2)
ipcs(1)