ipcs.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)ipcs.1	8.1	9/11/90
.\" SCCSID: @(#)ipcs.1	8.1	9/11/90
.TH ipcs 1
.SH Name
ipcs \- report interprocess communication facilities status
.SH Syntax
.B
ipcs [\|\fIoptions\fR\|]
.SH Description
.NX R "ipcs command"
.NX R "interprocess communication package" "reporting status"
.NX R "message queue" "reporting status"
.NX R "semaphore set" "reporting status"
.NX R "shared memory" "reporting status"
The
.Pn ipcs
command provides information about active,
interprocess communication facilities,
message queues, shared memory, and semaphores
that are currently active in the system.
.SH Options
.NXR "ipcs command" "options"
The information is displayed in columns and
is controlled by the following
.IR options :
.IP \fB\-m\fR
Displays information about active shared memory segments
.IP \fB\-q\fR 
Displays information about active message queues
.IP \fB\-s\fR 
Displays information about active semaphores
.PP
If any of the options
.B \-q,
.B \-m,
or
.RB \-s
are specified, information about only those indicated are printed.
If none of these three is specified, information about all three are
printed.
.IP \fB\-a\fR 
Uses all print
.IR options
(shorthand notation for
.B \-b, \-c, \-o, \-p
and
.BR \-t )
.IP \fB\-b\fR 
Displays the 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)  
.IP \fB\-C\fR 
Uses the specified core file (next argument) in place of 
.PN /dev/kmem
.IP \fB\-c\fR 
Displays creator's login name and group name  
.IP \fB\-N\fR o.3i 
Uses the specified 
.I namelist
(next argument) in place of
.PN /vmunix
.IP \fB\-o\fR 
Displays the outstanding usage information  (number of messages in queue, 
size of each and number of processes attached to shared memory segments)
.IP \fB\-p\fR 
Displays the process ID 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) 
.IP \fB\-t\fR 
Displays all time statistics (time of the last control operation that
changed the access permissions for all facilities, time of last
.PN msgsnd
and last
.PN msgrcv
on message queues, last
.PN shmat
and last
.PN shmdt
on shared memory, last 
.MS semop 2 
on semaphores) 
.PP
The column headings and the meaning of the columns in an
.PN ipcs
listing are given below.
The letters in parentheses indicate the
.I options
that cause the corresponding heading to appear;
.B all
means that the heading always appears.  
.NXR "ipcs command" "column headings listed"
Note that these
.I options
only determine what information is provided for each facility; they do
.I not
determine which facilities are listed.
.TP 20
T (all)	
Type of facility:
.RS
.TP
q
Message queue
.TP
m
Shared memory segment
.TP
s
Semaphore
.RE
.TP 20
ID (all)	
The identifier for the facility entry.
.TP 20
KEY (all)
The key used as an argument to
.PN msgget ,
.PN semget ,
or
.PN 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.
.TP 20
MODE (all)
The facility access modes and flags.
.sp .5
The mode consists of 11 characters.
The first two characters are interpreted as follows:
.RS
.TP
R
If the process is waiting on a
.PN msgrcv .
.TP
S
If a process is waiting on a
.PN msgsnd .
.TP
D
If the associated shared memory segment has been removed.  It 
disappears when the last process attached to the segment detaches it.
.TP
C
If the associated shared memory segment is to be clear when the first
attach is executed.
.fi
.TP
\-
If the corresponding special flag is
.I not
set.
.RE
.IP
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 write or alter the facility entry, and the last character
is currently unused.
.sp .5
The permissions are indicated as follows:
.RS
.TP
r
If read permission is granted
.TP
w
If write permission is granted
.TP
a
If alter permission is granted
.fi
.TP
\-
If the indicated permission is
.I not
granted
.RE
.TP 20
OWNER (all)  
The login name of the owner of the facility entry.
.TP 20
GROUP (all)  
The group name of the group of the owner of the facility entry.
.TP 20
CREATOR (a,c)
The login name of the creator of the facility entry.
.TP 20
CGROUP (a,c)
The group name of the group of the creator of the facility entry.
.TP 20
CBYTES (a,o)
The number of bytes in messages currently outstanding on the associated
message queue.
.TP 20
QNUM (a,o)
The number of messages currently
outstanding on the associated message queue.
.TP 20
QBYTES (a,b)
The maximum number of bytes allowed in messages outstanding
on the associated message queue.
.TP 20
LSPID (a,p)
The process ID of the last process to send a message to the associated
queue.
.TP 20
LRPID (a,p)
The process ID of the last process
to receive a message from the associated
queue.
.TP 20
STIME (a,t)
The time the last message was sent to the associated queue.
.TP 20
RTIME (a,t)
The time the last message was received from the associated queue.
.TP 20
CTIME (a,t)
The time the associated entry was created or changed.
.TP 20
NATTCH (a,o)
The number of processes attached to the associated shared memory
segment.
.TP 20
SEGSZ (a,b)
The size of the associated shared memory segment.
.TP 20
CPID (a,p)
The process ID of the creator of the shared memory entry.
.TP 20
LPID (a,p)
The process ID of the last process to attach or detach the shared memory
segment.
.TP 20
ATIME (a,t)
The time the last attach was completed to the associated shared memory
segment.
.TP 20
DTIME (a,t)
The time the last detach was completed on the associated shared memory
segment.
.TP 20
NSEMS (a,b)
The number of semaphores in the set associated with the semaphore
entry.
.TP 20
OTIME (a,t)
The time the last semaphore operation was completed on the set
associated with the semaphore entry.
.SH Restrictions
Things can change while
.PN ipcs
is running.  The picture it gives is only a close approximation to
reality.
.SH Files
.nf
/vmunix	system namelist
/dev/kmem	memory
/etc/passwd	user names
/etc/group	group names
.fi
.SH See Also
ipcrm(2), msgop(2), semop(2), shmop(2)