ipcs
TLDR
Show all active IPC facilities
$ ipcs
Show active shared memory segments$ ipcs --shmems
Show active message queues$ ipcs --queues
Show active semaphores$ ipcs --semaphores
Show details for specific resource by ID$ ipcs --shmems -i [resource_id]
Show system limits$ ipcs -l
Show summary of current usage$ ipcs -u
Show creator/owner information$ ipcs -c
Show last access times$ ipcs -t
SYNOPSIS
ipcs [options]
DESCRIPTION
ipcs displays information about System V IPC resources: shared memory segments, message queues, and semaphore arrays. It shows resource IDs, keys, owners, permissions, and sizes.
This is essential for monitoring IPC resource usage and identifying orphaned resources that should be cleaned up with ipcrm.
PARAMETERS
--shmems
Show shared memory segments--queues
Show message queues--semaphores
Show semaphore sets-i, --id ID
Show details for specific resource-l, --limits
Show system limits-u, --summary
Show usage summary-c, --creator
Show creator and owner UIDs/PIDs-p, --pid
Show PIDs of last operators-t, --time
Show last access times--human
Show sizes in human-readable format
CAVEATS
Only shows System V IPC, not POSIX IPC resources. User can only see resources they have permission to access (root sees all). Large numbers of resources may indicate a leak.
HISTORY
ipcs has been a standard Unix utility since System V IPC was introduced in the early 1980s. It remains the primary tool for inspecting System V IPC resources.
