Originální popis anglicky:
ipcs - report XSI interprocess communication facilities status
Návod, kniha: POSIX Programmer's Manual
ipcs [-qms][-a | -bcopt]
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.
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.)
None.
Not used.
- *
- The group database
- *
- The user database
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.
Default.
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:
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.
- -
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:
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:
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:
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
.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
- 0
- Successful completion.
- >0
- An error occurred.
Default.
The following sections are informative.
Things can change while
ipcs is running; the information it gives is
guaranteed to be accurate only when it was retrieved.
None.
None.
None.
The System Interfaces volume of IEEE Std 1003.1-2001,
msgrcv(),
msgsnd(),
semget(),
semop(),
shmat(),
shmdt(),
shmget()
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
.
