IPCS(1,C) AIX Commands Reference IPCS(1,C)
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ipcs
PURPOSE
Reports inter-process communication facility status.
SYNTAX
+- -m -q -s -+ +------------+ +- -C /dev/kmem -+ +---- -N /unix -----+
ipcs -| +----+ |-| +-- -a --+ |-| |-| |--|
+---| -m |---+ +-| +----+ |-+ +- -C corefile --+ +- -N kernel_image -+
^ | -q | | +-| -b |-+
| | -s | | ^| -c ||
| +----+ | || -o ||
+--------+ || -p ||
|| -t ||
|+----+|
+------+
DESCRIPTION
The ipcs command writes to the standard output information about active
inter-process communication facilities. If you do not specify any flags, the
ipcs command writes information in a short form about currently active message
queues, shared memory segments, and semaphores.
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 all designation means that the heading always appears.
These flags only determine what information is provided for each facility; they
do not determine which facilities will be 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
call to make the facility entry.
Note: The key of a shared memory segment is changed to IPC_PRIVATE
when the segment is removed until all processes attached to the
segment detach it.
Processed November 8, 1990 IPCS(1,C) 1
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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:
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 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 cleared when the
first attach is run.
- 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 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 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 name of the group that owns 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.
Note: For the OWNER, GROUP, CREATOR, and CGROUP, the user and group
IDs display instead of the login names.
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.
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IPCS(1,C) AIX Commands Reference IPCS(1,C)
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 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.
FLAGS
-a Uses the -b, -c, -o, -p and -t flags.
-b Writes the maximum number of bytes in messages on queue for message
queues, the size of segments for shared memory, and the number of
semaphores in each semaphores set.
-c Writes the login name and group name of the user that made the
facility.
-Ccorefile Uses the file corefile in place of the file /dev/kmem. The
corefile is a memory image file produced by the Ctrl-(left)Alt-Pad7
key sequence.
-m Writes information about active shared memory segments.
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IPCS(1,C) AIX Commands Reference IPCS(1,C)
-Nkernel-image
Uses the specified kernel-image (/unix is the default).
-o Writes the following usage information:
o Number of messages on queue
o Total number of bytes in messages in queue for message queues
o Number of processes attached to shared memory segments.
-p Writes the following:
o Process number of the last process to send or receive a message
on message queues
o Process number of the process that created the shared memory
segment
o 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:
o Time of the last control operation that changed the access
permissions for all facilities
o Time of the last msgsnd and last msgrcv system calls message
queues
o Time of the last shmat and last shmdt system calls on shared
memory
o Time of the last semop system call on semaphore sets.
FILES
/unix System kernel image.
/dev/kmem Memory.
/etc/passwd User names.
/etc/group Group names.
RELATED INFORMATION
See the ipcs, msgrcv, msgsnd, semop, shmat, and shmdt system calls in AIX
Operating System Technical Reference.
See "Memory Dump Services" in Managing the AIX Operating System.
Processed November 8, 1990 IPCS(1,C) 4