Manual pages › General commands (1)
ipcs(1)
report inter-process communication facilities status
From the original Amiga UNIX 2.1 manual. Some things it mentions may not be in this release.
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.
-N namelist
Use the file namelist in place of /stand/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 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 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 char-
acters 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 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 facil-
ity 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 mes-
sages 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 associ-
ated 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.