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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 dif-
       fer (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 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  con-
       trolled 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 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  mes-
              sages 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.)


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 Variables for the prece-
              dence 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 exam-
              ple, 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  writ-
              ten 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  mem-
       ory 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 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 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 correspond-
       ing 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 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  writ-
              ten 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  writ-
              ten 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  corre-
              sponding  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  writ-
              ten.

       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 .


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, Stan-
       dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base  Specifica-
       tions  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 Stan-
       dard,  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)