IPCS(1) (Interprocess Communication Utilities) IPCS(1)
NAME
ipcs - report inter-process communication facilities status
SYNOPSIS
ipcs [ options ]
DESCRIPTION
ipcs prints certain information about active inter-process
communication facilities. Without options, information is
printed 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 following options:
-q Print information about active message queues.
-m Print information about active shared memory
segments.
-s Print information about active semaphores.
If any of the options -q, -m, or -s are specified,
information about only those indicated will be printed. If
none of these three are specified, information about all
three will be printed subject to these options:
-b Print 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 Print creator's login name and group name. See below.
-o Print 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.)
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-p Print 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 Print 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 semop(2) on semaphores.) See below.
-a Use all print options. (This is a shorthand notation
for -b, -c, -o, -p, and -t.)
-C corefile
Use the file corefile in place of /dev/kmem.
-N namelist
Use the file namelist in place of /unix.
The column headings and the meaning of the columns in an
ipcs 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 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 IPCPRIVATE when the
segment has been removed until all processes
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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.
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.
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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.
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.
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IPCS(1) (Interprocess Communication Utilities) IPCS(1)
FILES
/unix system namelist
/dev/kmem memory
/etc/passwd user names
/etc/group group names
WARNING
If the user specifies either the -C or -N flag, the real and
effective UID/GID will be set to the real UID/GID of the
user invoking ipcs.
SEE ALSO
msgop(2), semop(2), shmop(2) in the Programmer's Reference
Manual.
BUGS
Things can change while ipcs is running; the picture it
gives is only a close approximation to reality.
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