IPCS(ADM) UNIX System V
Name
ipcs - reports the status of inter-process communication
facilities
Syntax
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 are displayed. If
none of the three options are specified, information about
all three are displayed.
-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 the meaning of columns in a listing.
-c Print creator's login name and group name. See below.
-o Display information on outstanding usage (number of
messages on queue, total number of bytes in messages on
queue, and the number of processes attached to shared
memory segments).
-p Display 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. It
displays the process ID of the creating process and the
process ID of the 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, and last semop(S) 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
The argument will be taken as the name of an alternate
namelist (/unix is the default).
-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 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. Note that ID is
``X'' for facilities created using creatsem(S) or sdget(S).
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 from 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.
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.
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.
Files
/unix system namelist
/dev/kmem memory
/etc/passwd user names
/etc/group group names
See Also
msgop(S), semop(S), shmop(S) in the Programmer's Reference
Manual
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.
Notes
Things can change while ipcs is running; the picture it
gives is only a close approximation.
Authorization
The behavior of this utility is affected by assignment of
the mem authorization, which is usually reserved for system
administrators. If you do not have this authorization, the
output will be restricted to data pertaining to your
activities only. Refer to the ``Using a Trusted System''
chapter of the User's Guide for more details.
(printed 8/23/89) IPCS(ADM)