ipcs - Report interprocess communication status

Synopsis

ipcs [-ETabcjmnopqstu]

Description

The ipcs utility reports information about existing interprocess communication (IPC) entries on the system and displays the output on standard output. The ipcs utility is shipped with public authority set to *EXCLUDE. The user must have *SERVICE special authority to run ipcs.

ipcs automatically reports some information for all entries that match the IPC mechanism specified. Additional information is reported based on the specified options.

If no IPC mechanism is specified, all five mechanisms are reported. An IPC mechanism is specified by using the -m option for shared memory, -n option of named semaphores, -s option for semaphores sets, -q option for message queues, or -u option for unnamed sempahores.

The following information is reported for every shared memory, semaphore set, and message queue entry:

The type of the mechanism (column T).
The id of the entry in decimal form (column ID).
The key of the entry in hexadecimal form (column KEY).
The entry's access modes and flags (column MODE).
The user profile of the owner of the entry (column OWNER).
The group profile of the owner of the entry (column GROUP).

The following information is reported for every named semaphore entry:

The type of the mechanism (column T).
The title for the semaphore (column TITLE).
The entry's access modes and flags (column MODE).

The following information is reported for every unnamed semaphore entry:

The type of the mechanism (column T).
The title for the semaphore (column TITLE).

Warning: Running ipcs locks system-scoped resources that can affect the performance of other IPC operations.

Options

The following options are used to select the IPC mechanism to report on.

-m: Show the shared memory entries on the system.
-n: Show the named semaphore entries on the system.
-q: Show the message queue entries on the system.
-s: Show the semaphore set entries on the system.
-u: Show the unnamed semaphore entries on the system.

The following options select the additional information that is reported for the IPC mechanism.

-a: Report all information as if the -b, -c, -o, -p, and -t options were specified.
-b: Display the maximum allowable size. If message queues are specified, the report includes the QBYTES column. If shared memory is specified, the report includes the SEGSZ column. If semaphore sets are specified, the report includes the NSEMS column. If named semaphores or unnamed semaphores are specified, the report includes the VALUE and NWAITERS columns.
-c: Display the user profile and group profile of the creator of the entry. For all mechanisms, the report includes the CREATOR and CGROUP columns.
-E: Display extended information. If message queues are specified, the report includes the WPID, WTID, MSGTYPE, and SIZE columns. If shared memory is specified, the report includes the APID, NUMATT, and PAGESZ columns. If semaphore sets are specified, the report includes the SEMNUM, SEMVAL, LOPID, WAITZ, WAITP, and WAITVAL columns. If named semaphores are specified, the report includes the NAME, LPOST, LWAIT, WAITER, JOB, and THREAD columns. If unnamed semaphores are specified, the report includes the LPOST, LWAIT, WAITER, JOB, and THREAD columns.
Since this level of detail is not available on other systems, this option is kept separate from the -a option. When this option is specified, at least one row is added for each entry.
-j: Display the qualified job name instead of the process ID when the -E option is also specified. If message queues are specified, the report includes the WJOBID column instead of WPID. If shared memory is specifed, the report includes the AJOBID column instead of APID. If semaphore sets are specified, the report includes the LOJOBID column instead of LOPID, the WAITZJID column instead of WAITZ, and the WAITPJID column instead of WAITP.
-o: Display information about outstanding usage. If message queues are specified, the report includes the CBYTES and QNUM columns. If shared memory is specified, the report includes the NATTCH column.
-p: Display process ID information. If message queues are specified, the report includes the LSPID and LRPID columns. If shared memory is specified, the report includes the CPID and LPID columns.
-t: Display time information. If message queues are specified, the report includes the CTIME, RTIME, and STIME columns. If shared memory is specified, the report includes the CTIME, ATIME, and DTIME columns. If semaphore sets are specified, the report includes the CTIME and OTIME columns.
-T: Display thread information. If message queues are specified, the report includes the LSTID and LRTID columns. If shared memory is specified, the report includes the CTID and LTID columns. If semaphore sets are specified and the -E option is specified, the report includes the LOTID, WAITZTID, and WAITPTID columns.

Operands

There are no operands.

Extended description

Listed below are descriptions for all of the columns that can be reported in the output. After the column name, the options that display the column are shown. A value of "default" means that the column is always displayed, no matter what option is specified.

AJOBID (-Ej)

The qualified job name of the jobs attached to the shared memory segment.

ATIME (-t, -a)

The last time a job attached to the shared memory segment.

APID (-E)

The process ID of the job or jobs attached to the shared memory segment.

CBYTES (-o, -a)

The total number of bytes in the messages currently on the message queue.

CGROUP (-c, -a)

The group profile of the creator of the entry.

CPID (-p, -a)

The process ID of the job that created the shared memory segment.

CTID (-T)

The thread ID of the thread that created the shared memory segment.

CREATOR (-c, -a)

The user profile of the creator of the entry.

CTIME (-t, -a)

The last time the entry was either created or the owner or permissions, or both, were changed.

DTIME (-t, -a)

The last time a job detached from the shared memory segment.

GROUP (default)

The group profile of the owner of the entry.

ID (default)

The id of the entry in decimal.

JOB (-E)

The fully-qualified job name of the job waiting on the named semaphore or unnamed semaphore.

KEY (default)

The key of the entry in hexadecimal.

LOJOBID (-Ej)

The qualified job name of the last job to change the value of the semaphore using semop().

LOPID (-E)

The process ID of the last job to change the value of the semaphore using semop().

LOTID (-TE)

The thread ID of the last thread to change the value of the semaphore using semop().

LPID (-p, -a)

The process ID of the last job to attach or detach from the shared memory segment or change the semaphore value.

LPOST (-E)

The fully-qualified job name and thread id of the last thread to post the named semaphore or unnamed semaphore.

LRPID (-p, -a)

The process ID of the last job to receive a message from the message queue using msgrcv().

LRTID (-T)

The thread ID of the last thread to receive a message from the message queue using msgrcv().

LSPID (-p, -a)

The process ID of the last job to send a message to the message queue using msgsnd().

LSTID (-T)

The thread ID of the last thread to send a message to the message queue using msgsnd().

LTID (-T)

The thread ID of the last thread to attach or detach from the shared memory segment.

LWAIT (-E)

The fully-qualified job name and thread id of the last thread to wait for the named semaphore or unnamed semaphore.

MODE (default)

An 11 character field that provides information about the state and permissions of the entry.

The first character can be one of the following:

D: The entry has sustained damage, and no operations can be performed on it. The entry should only be marked damaged if an internal error has occurred.
T: The entry is a shared memory segment and the segment uses teraspace storage.
Y: The entry is a shared memory segment and the segment uses teraspace storage and the entry has sustained damage.
-

The second character can be one of the following:

R: The entry is a message queue and a thread is waiting on a call to msgrcv().
S: The entry is a message queue and a thread is waiting on a call to msgsnd().
D: The entry is a shared memory segment and the shared memory segment is marked to be removed when all the jobs detach from the shared memory.
-: None of the above applies.

The next nine characters are interpreted as three sets of three permissions each. The first set refers to the owner's permissions, the second set to group's permissions, and the third set to other's permissions. Within each set, the first character indicates permission to read, the second character indicates permission to write, and the last character is currently unused.

The permissions are indicated as follows:

r: If read permission is granted.
w: If write permission is granted.
-: If the indicated permission is not granted.

MSGTYPE (-E)

The type of the messages that are currently on the message queue.

NAME (-E)

The path name of the named semaphore.

NATTCH (-o, -a)

The current number of attaches to the shared memory segment.

NUMATT (-E)

The number of times the job is attached to the shared memory segment.

NSEMS (-b, -a)

The number of semaphores in the semaphore set.

NWAITERS (-b, -a)

The number of threads waiting on the named semaphore or unnamed semaphore.

OTIME (-t, -a)

The last time that semop() was called using the semaphore set.

OWNER (default)

The user profile of the owner of the entry.

PAGESZ (-E)

The page size (in bytes) of the storage backing the shared memory segment.

QBYTES (-b, -a)

The maximum number of bytes allowed on the message queue.

QNUM (-o, -a)

The number of messages currently on the message queue.

RTIME (-t, -a)

The last time a msgrcv() was called using the message queue.

SEGSZ (-b, -a)

The size of the shared memory segment.

SEMNUM (-E)

The semaphore number in the semaphore set.

SEMVAL (-E)

The value of the semaphore.

SIZE (-E)

The size of the message on the message queue.

STIME (-t, -a)

The last time a msgsnd() was called using the message queue.

T (default)

The entry type. The value is M for a shared memory segment, N for a named semaphore, Q for a message queue, S for a semaphore set, or U for an unnamed semaphore.

THREAD (-E)

The thread ID of the thread waiting on the named semaphore or unnamed semaphore.

TITLE (default)

The title of the named semaphore or unnamed semaphore.

VALUE (-b, -a)

The current value of the named semaphore or unnamed semaphore.

WAITER (-E)

The index number of the thread waiting on the named semaphore or unnamed semaphore.

WAITP (-E)

The process ID of the job waiting for the semaphore value to reach a positive number.

WAITPJID (-Ej)

The qualified job name of the job waiting for the semaphore value to reach a positive number.

WAITPTID (-ET)

The thread ID of the thread or threads waiting for the semaphore value to reach a positive number.

WAITVAL (-E)

The value that the thread is waiting for the semaphore to reach.

WAITZ (-E)

The process ID of the job waiting for the semaphore value to reach zero.

WAITZJID (-Ej)

The qualified job name of the job waiting for the semaphore value to reach zero.

WAITZTID (-ET)

The thread ID of the thread or thread waiting for the semaphore value to reach zero.

WJOBID (-Ej)

The qualified job names of the jobs waiting to receive a message.

WPID (-E)

The process ID of the job or jobs waiting to receive a message.

WTID (-E)

The thread ID of the thread waiting to receive a message.

Exit status

0 on success
>0 if an error occurs