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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
IPCS(1P) POSIX Programmer's Manual IPCS(1P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
ipcs — report XSI interprocess communication facilities status
ipcs [−qms] [−a|−bcopt]
The ipcs utility shall write information about active interprocess
communication facilities.
Without options, information shall be written in short format for
message queues, shared memory segments, and semaphore sets that are
currently active in the system. Otherwise, the information that is
displayed is controlled by the options specified.
The ipcs utility shall conform to the Base Definitions volume of
POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
The ipcs utility accepts the following options:
−q Write information about active message queues.
−m Write information about active shared memory segments.
−s Write information about active semaphore sets.
If −q, −m, or −s are specified, only information about those
facilities shall be written. If none of these three are specified,
information about all three shall be written subject to the following
options:
−a Use all print options. (This is a shorthand notation for
−b, −c, −o, −p, and −t.)
−b Write information on maximum 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.)
−c Write creator's user name and group name; see below.
−o Write 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 Write process number information. (Process ID of the last
process to send a message and process ID of the last
process to receive a message on message queues, process ID
of the creating process, and process ID of the last process
to attach or detach on shared memory segments.)
−t Write time information. (Time of the last control operation
that changed the access permissions for all facilities,
time of the last msgsnd() and msgrcv() operations on
message queues, time of the last shmat() and shmdt()
operations on shared memory, and time of the last semop()
operation on semaphores.)
None.
Not used.
* The group database
* The user database
The following environment variables shall affect the execution of
ipcs:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base Definitions
volume of POSIX.1‐2008, Section 8.2, Internationalization
Variables for the precedence of internationalization
variables used to determine the values of locale
categories.)
LC_ALL If set to a non-empty string value, override the values of
all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of sequences of
bytes of text data as characters (for example, single-byte
as opposed to multi-byte characters in arguments).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
TZ Determine the timezone for the date and time strings
written by ipcs. If TZ is unset or null, an unspecified
default timezone shall be used.
Default.
An introductory line shall be written with the format:
"IPC status from %s as of %s\n", <source>, <date>
where <source> indicates the source used to gather the statistics and
<date> is the information that would be produced by the date command
when invoked in the POSIX locale.
The ipcs utility then shall create up to three reports depending upon
the −q, −m, and −s options. The first report shall indicate the
status of message queues, the second report shall indicate the status
of shared memory segments, and the third report shall indicate the
status of semaphore sets.
If the corresponding facility is not installed or has not been used
since the last reboot, then the report shall be written out in the
format:
"%s facility not in system.\n", <facility>
where <facility> is Message Queue, Shared Memory, or Semaphore, as
appropriate. If the facility has been installed and has been used
since the last reboot, column headings separated by one or more
<space> characters and followed by a <newline> shall be written as
indicated below followed by the facility name written out using the
format:
"%s:\n", <facility>
where <facility> is Message Queues, Shared Memory, or Semaphores, as
appropriate. On the second and third reports the column headings need
not be written if the last column headings written already provide
column headings for all information in that report.
The column headings provided in the first column below and the
meaning of the information in those columns shall be given in order
below; the letters in parentheses indicate the options that shall
cause the corresponding column to appear; ``all'' means that the
column shall always appear. Each column is separated by one or more
<space> characters. Note that these options only determine what
information is provided for each report; they do not determine which
reports are written.
T (all) Type of facility:
q Message queue.
m Shared memory segment.
s Semaphore.
This field is a single character written using the format
%c.
ID (all) The identifier for the facility entry. This field shall
be written using the format %d.
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.
This field shall be written using the format 0x%x.
MODE (all) The facility access modes and flags. The mode shall
consist of 11 characters that are interpreted as follows.
The first character shall be:
S If a process is waiting on a msgsnd() operation.
− If the above is not true.
The second character shall be:
R If a process is waiting on a msgrcv() operation.
C or − If the associated shared memory segment is to be
cleared when the first attach operation is
executed.
− If none of the above is true.
The next nine characters shall be 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 usergroup 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 a minus-sign ('−').
The permissions shall be 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.
The first character following the permissions specifies
if there is an alternate or additional access control
method associated with the facility. If there is no
alternate or additional access control method associated
with the facility, a single <space> shall be written;
otherwise, another printable character is written.
OWNER (all) The user name of the owner of the facility entry. If the
user name of the owner is found in the user database, at
least the first eight column positions of the name shall
be written using the format %s. Otherwise, the user ID
of the owner shall be written using the format %d.
GROUP (all) The group name of the owner of the facility entry. If the
group name of the owner is found in the group database,
at least the first eight column positions of the name
shall be written using the format %s. Otherwise, the
group ID of the owner shall be written using the format
%d.
The following nine columns shall be only written out for message
queues:
CREATOR (a,c)
The user name of the creator of the facility entry. If
the user name of the creator is found in the user
database, at least the first eight column positions of
the name shall be written using the format %s.
Otherwise, the user ID of the creator shall be written
using the format %d.
CGROUP (a,c)
The group name of the creator of the facility entry. If
the group name of the creator is found in the group
database, at least the first eight column positions of
the name shall be written using the format %s.
Otherwise, the group ID of the creator shall be written
using the format %d.
CBYTES (a,o)
The number of bytes in messages currently outstanding on
the associated message queue. This field shall be written
using the format %d.
QNUM (a,o) The number of messages currently outstanding on the
associated message queue. This field shall be written
using the format %d.
QBYTES (a,b)
The maximum number of bytes allowed in messages
outstanding on the associated message queue. This field
shall be written using the format %d.
LSPID (a,p) The process ID of the last process to send a message to
the associated queue. This field shall be written using
the format:
"%d", <pid>
where <pid> is 0 if no message has been sent to the
corresponding message queue; otherwise, <pid> shall be
the process ID of the last process to send a message to
the queue.
LRPID (a,p) The process ID of the last process to receive a message
from the associated queue. This field shall be written
using the format:
"%d", <pid>
where <pid> is 0 if no message has been received from the
corresponding message queue; otherwise, <pid> shall be
the process ID of the last process to receive a message
from the queue.
STIME (a,t) The time the last message was sent to the associated
queue. If a message has been sent to the corresponding
message queue, the hour, minute, and second of the last
time a message was sent to the queue shall be written
using the format %d:%2.2d:%2.2d. Otherwise, the format
" no-entry" shall be written.
RTIME (a,t) The time the last message was received from the
associated queue. If a message has been received from
the corresponding message queue, the hour, minute, and
second of the last time a message was received from the
queue shall be written using the format %d:%2.2d:%2.2d.
Otherwise, the format " no-entry" shall be written.
The following eight columns shall be only written out for shared
memory segments.
CREATOR (a,c)
The user of the creator of the facility entry. If the
user name of the creator is found in the user database,
at least the first eight column positions of the name
shall be written using the format %s. Otherwise, the
user ID of the creator shall be written using the format
%d.
CGROUP (a,c)
The group name of the creator of the facility entry. If
the group name of the creator is found in the group
database, at least the first eight column positions of
the name shall be written using the format %s.
Otherwise, the group ID of the creator shall be written
using the format %d.
NATTCH (a,o)
The number of processes attached to the associated shared
memory segment. This field shall be written using the
format %d.
SEGSZ (a,b) The size of the associated shared memory segment. This
field shall be written using the format %d.
CPID (a,p) The process ID of the creator of the shared memory entry.
This field shall be written using the format %d.
LPID (a,p) The process ID of the last process to attach or detach
the shared memory segment. This field shall be written
using the format:
"%d", <pid>
where <pid> is 0 if no process has attached the
corresponding shared memory segment; otherwise, <pid>
shall be the process ID of the last process to attach or
detach the segment.
ATIME (a,t) The time the last attach on the associated shared memory
segment was completed. If the corresponding shared memory
segment has ever been attached, the hour, minute, and
second of the last time the segment was attached shall be
written using the format %d:%2.2d:%2.2d. Otherwise, the
format " no-entry" shall be written.
DTIME (a,t) The time the last detach on the associated shared memory
segment was completed. If the corresponding shared memory
segment has ever been detached, the hour, minute, and
second of the last time the segment was detached shall be
written using the format %d:%2.2d:%2.2d. Otherwise, the
format " no-entry" shall be written.
The following four columns shall be only written out for semaphore
sets:
CREATOR (a,c)
The user of the creator of the facility entry. If the
user name of the creator is found in the user database,
at least the first eight column positions of the name
shall be written using the format %s. Otherwise, the
user ID of the creator shall be written using the format
%d.
CGROUP (a,c)
The group name of the creator of the facility entry. If
the group name of the creator is found in the group
database, at least the first eight column positions of
the name shall be written using the format %s.
Otherwise, the group ID of the creator shall be written
using the format %d.
NSEMS (a,b) The number of semaphores in the set associated with the
semaphore entry. This field shall be written using the
format %d.
OTIME (a,t) The time the last semaphore operation on the set
associated with the semaphore entry was completed. If a
semaphore operation has ever been performed on the
corresponding semaphore set, the hour, minute, and second
of the last semaphore operation on the semaphore set
shall be written using the format %d:%2.2d:%2.2d.
Otherwise, the format " no-entry" shall be written.
The following column shall be written for all three reports when it
is requested:
CTIME (a,t) The time the associated entry was created or changed. The
hour, minute, and second of the time when the associated
entry was created shall be written using the format
%d:%2.2d:%2.2d.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
Things can change while ipcs is running; the information it gives is
guaranteed to be accurate only when it was retrieved.
None.
None.
None.
ipcrm(1p)
The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2008, msgrcv(3p), msgsnd(3p),
semget(3p), semop(3p), shmat(3p), shmdt(3p), shmget(3p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 IPCS(1P)
Pages that refer to this page: ipcrm(1p)