.\"	$NetBSD: ipcs.1,v 1.22 2025/11/15 22:46:25 uwe Exp $
.\"
.\" Copyright (c) 1994 SigmaSoft, Th. Lockert
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd November 14, 2025
.Dt IPCS 1
.Os
.Sh NAME
.Nm ipcs
.Nd report System V interprocess communication facilities status
.Sh SYNOPSIS
.Nm
.Op Fl abcMmopQqSsTt
.Sh DESCRIPTION
The
.Nm
program provides information on System V interprocess communication
.Pq Tn IPC
facilities on the system.
.Pp
The options are as follows:
.Bl -tag -width Fl
.It Fl a
Show the maximum amount of information possible when displaying active
message queues, shared memory segments, and semaphores.
This is shorthand for specifying the
.Fl b ,
.Fl c ,
.Fl o ,
.Fl p ,
and
.Fl t
options.
.It Fl b
Show the maximum allowed sizes for active
message queues, shared memory segments, and semaphores.
The
.Dq maximum allowed size
is the maximum number of bytes in a message on a message queue,
the size of a shared memory segment,
or the number of semaphores in a set of semaphores.
.It Fl c
Show the creator's name and group for active
message queues, shared memory segments, and semaphores.
.It Fl M
Display system information about shared memory.
.It Fl m
Display information about active shared memory segments.
.It Fl o
Show outstanding usage for active
message queues, and shared memory segments.
The
.Dq outstanding usage
is the number of messages in a message queue, or the number
of processes attached to a shared memory segment.
.It Fl p
Show the
.Tn PID
information for active
message queues, shared memory segments, and semaphores.
The
.Dq Tn PID No information
is the last process to send a message to or receive a message from a
message queue,
the last process to attach to or detach a shared memory segment,
or the process that created a semaphore.
.It Fl Q
Display system information about messages queues.
.It Fl q
Display information about active message queues.
.It Fl S
Display system information about semaphores.
.It Fl s
Display information about active semaphores.
.It Fl T
Display system information about
message queues, shared memory segments, and semaphores.
This is shorthand for specifying the
.Fl M ,
.Fl Q ,
and
.Fl S
options.
.It Fl t
Show access times for active
message queues, shared memory segments, and semaphores.
The access times is the time of the last control operation on an
.Tn IPC
object,
the last send or receive of a message,
the last attach or detach of a shared memory segment,
or the last operation on a semaphore.
.El
.Pp
If none of the
.Fl M ,
.Fl m ,
.Fl Q ,
.Fl q ,
.Fl S ,
.Fl s ,
or
.Fl T
options are specified, information about all active
.Tn IPC
facilities is listed.
.Pp
The output generated by
.Nm
if passed the
.Fl M ,
.Fl Q ,
and
.Fl S
options is self-explanatory.
For the other options, the output consists of a series
of columns depending on the facility in question as
well as which of the various supported flags were
given.
.Pp
The meaning of each column as identified by the column
heading is as follows:
.Bl -tag -width ".Sy WWWWWW"
.It Sy T
The type of facility, identified as:
.Pp
.Bl -tag -width Sy -offset indent -compact
.It Sy m
shared memory segment
.It Sy s
semaphore
.It Sy q
message queue
.El
.It Sy ID
The identifier, suitable to be passed to, e.g.,
.Xr ipcrm 1 .
.It Sy KEY
The key passed to, e.g.,
.Xr msgget 2 ,
.Xr semget 2 ,
or
.Xr shmget 2 ;
often created using
.Xr ftok 3 .
.It Sy MODE
A string of 11 characters representing the access mode
and flags for the facility.
.Pp
On
.Nx ,
the first two characters are always
.Ql \- .
.Pp
The remaining 9 characters are similar to typical file
permissions in that three characters each refer to
owner-, group-, and other permissions of the facility
entry with the following meaning:
.Pp
.Bl -tag -width Sy -offset indent -compact
.It Sy r
read permission
.It Sy w
write permission
.It Sy a
alter permission
.Pq the ability to change control information such as the owner or permissions
.El
.It Sy OWNER
The user name
.Po
or, if no user name can be found,
.Tn UID
.Pc
of the owner of the facility entry.
.It Sy GROUP
The group name
.Po
or, if no group name can be found,
.Tn GID
.Pc
of the group owner of the facility entry.
.It Sy CREATOR
The user name
.Po
or, if no user name can be found,
.Tn UID
.Pc
of the creator of the facility entry.
.It Sy CGROUP
The group name
.Po
or, if no group name can be found,
.Tn GID
.Pc
of the creator group owner of the facility entry.
.El
.Pp
Following this, the columns printed will differ for
each of the facilities.
.Pp
Times are displayed as if with
.Xr strftime 3
.Ql %k:%M:%S
format
.Pq no leading zero for the hours value
in the time zone described by the
.Ev TZ
environment variable or
.Pa /etc/localtime .
If no time is available for the given event, the
string
.Ql no-entry
is used instead.
.Ss Message Queues
.Bl -tag -width ".Sy WWWWWW" -compact
.It Sy CBYTES
The total number of bytes left in the message queue.
.It Sy QNUM
The number of messages left in the message queue.
.It Sy QBYTES
The maximum number of bytes in the message queue.
.It Sy LSPID
The
.Tn PID
of the last process to send a message.
.It Sy LRPID
The
.Tn PID
of the last process to receive a message.
.It Sy STIME
The time of last
.Xr msgsend 2 .
.It Sy RTIME
The time of last
.Xr msgrcv 2 .
.It Sy CTIME
The time the message queue was created or last modified.
.El
.Ss Shared Memory
.Bl -tag -width ".Sy WWWWWW" -compact
.It Sy NATTCH
The number of current attaches.
.It Sy SEGSZ
The size of the shared memory segment in bytes.
.It Sy CPID
The
.Tn PID
of the process that created the shared memory segment.
.It Sy LPID
The
.Tn PID
of the last shm operation.
.It Sy ATIME
The time of last
.Xr shmat 2 .
.It Sy DTIME
The time of last
.Xr shmdt 2 .
.It Sy CTIME
The time the shared memory segment was created
or last modified.
.El
.Ss Semaphores
.Bl -tag -width ".Sy WWWWWW" -compact
.It Sy NSEMS
The number of semaphores in the set.
.It Sy OTIME
The time of last
.Xr semop 2 .
.It Sy CTIME
The time the semaphore set was created or last
modified.
.El
.Sh CAVEATS
System data structures may change while
.Nm
is running; the output of
.Nm
is not guaranteed to be consistent.
.Sh SEE ALSO
.Xr ipcrm 1 ,
.Xr msgctl 2 ,
.Xr msgget 2 ,
.Xr msgrcv 2 ,
.Xr msgsnd 2 ,
.Xr semctl 2 ,
.Xr semget 2 ,
.Xr semop 2 ,
.Xr shmat 2 ,
.Xr shmctl 2 ,
.Xr shmdt 2 ,
.Xr shmget 2 ,
.Xr ftok 3
.Sh AUTHORS
.An Thorsten Lockert Aq Mt tholo@sigmasoft.com
.Sh BUGS
The first two characters of the
.Sy MODE
are always set to
.Ql \-
on
.Nx .
On other platforms, these characters may indicate
additional state information about the given facility.