ipcs(1posix)
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 utility shall conform to the Base Definitions volume of
POSIX.12008, 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 POSIX.12008, 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 <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 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 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
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.12008, Chapter 8, Environment Variables, Section 12.2, Utility Syntax Guidelines The System Interfaces volume of POSIX.12008, 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 Electrical 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.kernel.org/doc/man-pages/reporting_bugs.html .
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