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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  facility   supports	the   Base   Definitions   volume   of
       IEEE Std 1003.1-2001, 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 sem‐
	      aphores.)

       -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 seg‐
	      ments.)

       -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.)

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  variables
	      that  are	 unset	or  null.  (See the Base Definitions volume of
	      IEEE Std 1003.1-2001, 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 spaces 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>s.  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 writ‐
	      ten 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 per‐
       mission 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; other‐
       wise, 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 mes‐
       sage 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 writ‐
	      ten 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 writ‐
	      ten 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	 sema‐
	      phore 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 .

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
       The  System  Interfaces	volume	of   IEEE Std 1003.1-2001,   msgrcv(),
       msgsnd(), semget(), semop(), shmat(), shmdt(), shmget()

COPYRIGHT
       Portions	 of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating	System	Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003	by  the	 Institute  of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .

IEEE/The Open Group		     2003			      IPCS(1P)
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