ipcs

display information about active IPC facilities 

Command

SYNOPSIS

ipcs [-abcmopqstT]

DESCRIPTION

ipcs prints information about active interprocess communication (IPC) facilities. Without options, information is printed in short format for message queues, shared memory, and semaphores. The following options control the information that ipcs displays.

Things may change while ipcs is running; the information it gives is guaranteed to be accurate only at the time it was retrieved.

Options

-a  

uses all print options except -T. (This is a shorthand notation for -bcopt.)

-b  

prints information on biggest 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 Output for meaning of columns in a listing.

-c  

prints creator's login name and group name. See Output.

-m  

prints information about active shared memory segments.

-o  

prints information on outstanding usage: number of messages in queue and total number of bytes in messages on queue for message queues and number of processes attached to shared memory segments.

-p  

prints 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 shared memory segments. See Output.

-q  

prints information about active message queues.

-s  

prints information about active semaphores.

-t  

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

-T  

prints message types for all messages on message queues.

Note:

If -q, -m, or -s are specified, ipcs prints only that information about the IPCs unique to the option. If none of these three options are specified, ipcs prints information about all IPCs, subject to the output options.

Output

The column headings and the meaning of the columns in output listing from ipcs are discussed below. Letters in parentheses indicate the options that cause the heading to appear; all means that the heading always appears.

T (all)  

Type of the facility

q  

message queue

m  

shared memory segment

s  

semaphore

ID (all)  

The identifier for the facility entry.

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 after the segment is removed and before all processes attached to the segment detach it.

MODE (all)  

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

R A process is waiting on a msgrcv().
S A process is waiting on a msgsnd().
D The associated shared memory segment has been removed. It disappears when the last process attached to the segment detaches it.
C The associated shared memory segment is to be cleared when the first attach is executed.
- The corresponding special flag is not set.

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 as follows:

r Read permission is granted.
w Write permission is granted.
a Alter permission is granted.
- 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 group 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 group 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 when 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 was completed to the associated shared memory segment.

DTIME (-a, -t)  

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

NSEMS (-a, -b)  

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

OTIME (-a, -t)  

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

AVAILABILITY

PTC MKS Toolkit for Power Users
PTC MKS Toolkit for System Administrators
PTC MKS Toolkit for Developers
PTC MKS Toolkit for Interoperability
PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Professional Developers 64-Bit Edition
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition

SEE ALSO

Commands:
ipcrm

Functions:
semctl(), semget(), semop(), shmctl(), shmget()

PTC MKS Toolkit 10.4 Documentation Build 39.