ipcs(1)

Synopsis

Description

Note that information is displayed only for objects to which the user has read access.

A user with the appropriate privileges is able to override the read access restriction and display information on all objects.

Note that options that apply to shared memory also apply to dynamic shared memory.

Without options, information is printed in short format for message queues, shared memory, and semaphores that are currently active in the system. Otherwise, the information that is displayed is controlled by the following options:

-q

Print information about active message queues.

-m

Print information about active shared memory segments.

-s

Print information about active semaphores.

-d

Print information about dynamic shared memory segments.

If -q, -m, -s or -d are specified, information about only those indicated is printed. If none of these four are specified, information about all four is printed subject to these options:

-b

Print 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.) See below for meaning of columns in a listing.

-c

Print creator's login name and group name. See below.

-o

Print 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

Print process number information. (Process ID of last process to send a message, process ID of last process to receive a message on message queues, process ID of creating process, and process ID of last process to attach or detach on dynamic and regular shared memory segments.) See below.

-t

Print time information. (Time of the last control operation that changed the access permissions for all facilities, time of last msgsnd and msgrcv operations on message queues, time of last shmat and shmdt operations on shared memory, and time of last semop operation on semaphores.) See below.

-a

Use all print options. (This is a shorthand notation for -b, -c, -o, -p, -t.)

-C corefile

Use the file corefile in place of /dev/kmem.

-N namelist

Use the file namelist in place of /stand/unix.

The column headings and the meaning of the columns in an ipcs listing are given below; the letters in parentheses indicate the options that cause the corresponding heading to appear; all means that the heading always appears. Note that these options only determine what information is provided for each facility; they do not determine which facilities are listed.

T (all)

Type of facility:

q

message queue

m

shared memory segment

d

dynamic shared memory segment

s

semaphore

ID (all)

The identifier for the facility entry.

KEY (all)

The key used as an argument to msgget, semget, shmget, or dshm_get to create the facility entry.

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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.

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MODE (all)

The facility access modes and flags. The mode consists of 11 characters that are interpreted as follows:

The first character is:

S

if a process is waiting on a msgsnd operation.

-

if the above is not true.

The second character is:

R

if a process is waiting on a msgrcv operation.

-

if the above is not true.

The next nine characters are 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 user-group 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 currently unused.

The permissions are 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.

OWNER (all)

The login name of the owner of the facility entry.

GROUP (all)

The group name of the owner of the facility entry.

CREATOR (a,c)

The login name of the creator of the facility entry.

CGROUP (a,c)

The group name of the creator of the facility entry.

CBYTES (a,o)

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

QNUM (a,o)

The number of messages currently outstanding on the associated message queue.

QBYTES (a,b)

The maximum number of bytes allowed in messages outstanding on the associated message queue.

LSPID (a,p)

The process ID of the last process to send a message to the associated queue.

LRPID (a,p)

The process ID of the last process to receive a message from the associated queue.

STIME (a,t)

The time the last message was sent to the associated queue.

RTIME (a,t)

The time the last message was received from the associated queue.

CTIME (a,t)

The time the associated entry was created or changed.

NATTCH (a,o)

The number of processes attached to the associated shared memory segment.

SEGSZ (a,b)

The size of the associated shared memory segment.

CPID (a,p)

The process ID of the creator of the shared memory entry.

LPID (a,p)

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

ATIME (a,t)

The time the last attach on the associated shared memory segment was completed.

DTIME (a,t)

The time the last detach on the associated shared memory segment was completed.

NSEMS (a,b)

The number of semaphores in the set associated with the semaphore entry.

OTIME (a,t)

The time the last semaphore operation on the set associated with the semaphore entry was completed.

Files

/stand/unix

system namelist

/dev/kmem

memory

/etc/passwd

user names

/etc/group

group names

References

Notices

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