ipcs shows information on the inter-process communication facilities for which the calling process has read access. By default, it shows information about all three resources: shared memory segments, message queues, and semaphore arrays.
Without options, the 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.
- -q : Write information about active message queues.
- -m : Write information about active shared memory segments.
- -s : Write information about active semaphore sets.
- -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;.
- -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.)
Examples on IPCS command:
1: To list all the IPC facility
All the IPC facility has unique key and identifier, which is used to identify an IPC facility.
2: To list all the Message Queue
To list all the Semaphores
To list all the Shared Memory
To get the detailed information about an IPC facility
- To lists the Limits for IPC facility
To list Creator and Owner Details for IPC Facility
To get the process ids that accessed IPC facility recently
To get the last Accessed Time
To get the status of current usage
ipcs command is a powerful tool for gaining insights into the inter-process communication facilities of a Unix-like operating system. By providing information about shared memory segments, message queues, and semaphore arrays,
ipcs assists in system monitoring, troubleshooting, resource management, and concurrency analysis. System administrators and developers can utilize this command to ensure efficient and secure communication between processes on their systems.