ipcs(1) UNIX System V(Interprocess Communication Utilities) ipcs(1)
NAME
ipcs - report inter-process communication facilities status
SYNOPSIS
ipcs [ options ]
DESCRIPTION
ipcs prints 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 -q, -m, or -s are specified, information about only those indicated is
printed. If none of these three are specified, information about all
three is printed subject to these options:
-b Print information on biggest allowable size: 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.
-p Print process number information: process ID of last process to
send a message, process ID of last process to receive a message on
message queues, 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, time of last shmat and
last shmdt on shared memory, time of last semop 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.
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-N namelist
Use the file namelist in place of /stand/unix.
-X Print information about XENIX interprocess communication, in
addition to the standard interprocess communication status. The
XENIX process information describes a second set of semaphores and
shared memory.
Note that the -p option does not print process number information for
XENIX shared memory, and the -t option does not print time information
about XENIX semaphores and shared memory.
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 are
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 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 A process is waiting on a msgrcv.
S A process is waiting on a msgsnd.
D The associated shared memory segment has been
removed. It will disappear when the last process
attached to the segment detaches it.
C The associated shared memory segment is to be
cleared when the first attach is executed.
- 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
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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 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.
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.
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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.
FILES
/stand/unix system namelist
/dev/kmem memory
/etc/passwd user names
/etc/group group names
NOTES
If the user specifies either the -C or -N flag, the real and effective
UID/GID is set to the real UID/GID of the user invoking ipcs.
Things can change while ipcs is running; the information it gives is
guaranteed to be accurate only when it was retrieved.
SEE ALSO
msgop(2), semop(2), shmop(2) in the Programmer's Reference Manual.
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