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IPCS(1P)		   POSIX Programmer's Manual		      IPCS(1P)

PROLOG
       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.

NAME
       ipcs — report XSI interprocess communication facilities status

SYNOPSIS
       ipcs [−qms] [−a|−bcopt]

DESCRIPTION
       The ipcs utility shall write information about active interprocess com‐
       munication facilities.

       Without	options, information shall be written in short format for mes‐
       sage queues, shared memory segments, and semaphore sets that  are  cur‐
       rently  active  in  the system. Otherwise, the information that is dis‐
       played is controlled by the options specified.

OPTIONS
       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 sem‐
		 aphores.)

OPERANDS
       None.

STDIN
       Not used.

INPUT FILES
	*  The group database

	*  The user database

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of ipcs:

       LANG	 Provide  a  default  value for the internationalization vari‐
		 ables that are unset or null. (See the Base Definitions  vol‐
		 ume  of POSIX.1‐2008, Section 8.2, Internationalization Vari‐
		 ables 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.

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       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 for‐
       mat:

	   "%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> char‐
       acters 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 col‐
       umn 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 corre‐
       sponding	 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  exe‐
			   cuted.

		   −	   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 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 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 facil‐
		   ity, 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 associ‐
		   ated	 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 writ‐
		   ten 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	corre‐
		   sponding  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 mes‐
		   sage	 was sent to the queue shall be written using the for‐
		   mat	%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 correspond‐
		   ing 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 writ‐
		   ten 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  for‐
		   mat %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 correspond‐
		   ing shared memory segment; otherwise, <pid>	shall  be  the
		   process ID of the last process to attach or detach the seg‐
		   ment.

       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  sec‐
		   ond	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 sec‐
		   ond 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 writ‐
		   ten 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 for‐
		   mat %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 sem‐
		   aphore set, the hour, minute, and second of the last	 sema‐
		   phore 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.

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

	0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       Things  can  change  while ipcs is running; the information it gives is
       guaranteed to be accurate only when it was retrieved.

EXAMPLES
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       ipcrm

       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(), msgsnd(),
       semget(), semop(), shmat(), shmdt(), shmget()

COPYRIGHT
       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 Electri‐
       cal 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.ker‐
       nel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group		     2013			      IPCS(1P)
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