ipcs(1p) — Linux manual page

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)

PROLOG         top

       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         top

       ipcs — report XSI interprocess communication facilities status

SYNOPSIS         top

       ipcs [-qms] [-a|-bcopt]

DESCRIPTION         top

       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.

OPTIONS         top

       The ipcs utility shall conform to the Base Definitions volume of
       POSIX.1‐2017, 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.)

OPERANDS         top

       None.

STDIN         top

       Not used.

INPUT FILES         top

        *  The group database

        *  The user database

ENVIRONMENT VARIABLES         top

       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.1‐2017, 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.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       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 <hyphen-
                   minus> ('-').

                   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.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

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

EXAMPLES         top

       None.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       ipcrm(1p)

       The Base Definitions volume of POSIX.1‐2017, Chapter 8,
       Environment Variables, Section 12.2, Utility Syntax Guidelines

       The System Interfaces volume of POSIX.1‐2017, msgrcv(3p),
       msgsnd(3p), semget(3p), semop(3p), shmat(3p), shmdt(3p),
       shmget(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       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               2017                          IPCS(1P)

Pages that refer to this page: ipcrm(1p)