ipcs(1)
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ipcs Command
report inter-process communication facilities status
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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 will be printed. If none of these
three are specified, information about all three will be printed.
-b Print biggest allowable size information. (Maximum number
of bytes in messages on queues 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 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.
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-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.)
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 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.
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
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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
/dgux system image (namelist)
/etc/passwd user names
/etc/group group names
SEE ALSO
dg_sys_info(2), msgop(2), semop(2), shmop(2) in the Programmer's
Reference for the DG/UX System
BUGS
Things can change while ipcs is running; the picture it gives is
only a close approximation to reality.
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