ipcs(1) CLIX ipcs(1)
NAME
ipcs - Reports interprocess communication facilities status
SYNOPSIS
ipcs [flag ... ]
FLAGS
-q Displays information about active message queues.
-m Displays information about active shared memory segments.
-s Displays information about active semaphores.
DESCRIPTION
The ipcs command displays certain information about active interprocess
communication facilities. Without flags, information is displayed in
short format for message queues, shared memory, and semaphores that are
currently active in the system. Otherwise, the information that is
displayed is controlled by the flags shown above.
If any of the flags -q, -m, or -s are specified, information about only
those indicated will be displayed. If none of these three are specified,
information about all three will be displayed subject to these flags:
-b Displays 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.) See below for meaning of
columns in a listing.
-c Displays creator's login name and group name. See below.
-o Displays 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 Displays process number information. (Process ID of last
process to send a message and process ID of last process to
receive a message on message queues and process ID of
creating process and process ID of last process to attach or
detach on shared memory segments.) See below.
-t Displays 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, last shmat() and last shmdt() on shared memory, last
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semop() on semaphores.) See below.
-a Uses all display flags. (This is a shorthand notation for
-b, -c, -o, -p, and -t.)
-C corefile Uses the file corefile in place of /dev/kmem.
-N namelist The argument will be taken as the name of an alternate
namelist (/unix is the default).
The column headings and the meaning of the columns in an ipcs listing are
given below; the letters in parentheses indicate the flags that cause the
corresponding heading to appear; all means that the heading always
appears. Note that these flags only determine what information is
provided for each facility; they do not determine which facilities will be
listed.
T (all) Type of the 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 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 characters are:
R If a process is waiting on a msgrcv().
S If a process is waiting on a msgsnd().
D If the associated shared memory segment has been removed.
It will disappear 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 executed.
- If the corresponding special flag is not set.
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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 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 when the associated entry was created or changed.
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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.
EXAMPLES
1. To display information about message queues only, including biggest
size, time information, and outstanding usage:
ipcs -qbot
2. To display all information available about interprocess
communications:
ipcs -a
3. To display information about interprocess communications contained in
the core file an using the process /testunix instead of /unix. This
is useful for debugging.
ipcs -C core -N /testunix
FILES
/unix System namelist
/dev/kmem
Memory
/etc/passwd
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Usernames
/etc/group
Group names
NOTES
Things can change while ipcs is running; the picture it gives is only a
close approximation to reality.
SECURITY CONSIDERATIONS
If your system is running CLIX-TS, this command will operate differently.
Refer to the CLIX-TS Secure Facilities User's Guide for more information.
DIAGNOSTICS
ipcs: no namelist
The argument to the -N flag does not exist.
ipcs: no memory file
The argument for the -C flag does not exist.
EXIT VALUES
The ipcs command exits with value of 0 if successful. If unsuccessful,
ipcs returns a value of 1.
RELATED INFORMATION
Functions: msgop(2), semop(2), shmop(2)
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