ipcs(1p)

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 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 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

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 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 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 corresponding 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.

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(P)