ipcmk

creates System V IPC resources

TLDR

Create a shared memory segment

$ ipcmk -M [segment_size_in_bytes]

Create a semaphore set

$ ipcmk -S [element_size]

Create a message queue

$ ipcmk -Q

Create shared memory with specific permissions

$ ipcmk -M [segment_size] -p [0644]

ipcmk creates System V IPC (Inter-Process Communication) resources. These resources allow processes to communicate and synchronize: shared memory enables direct data sharing, semaphores coordinate access to resources, and message queues enable asynchronous messaging.Created resources are identified by a key and ID, which can be viewed with ipcs and removed with ipcrm. Resources persist until explicitly removed or system reboot.

PARAMETERS

-M, --shmem SIZE

Create shared memory segment of specified size in bytes

-S, --semaphore COUNT

Create semaphore set with specified number of elements

-Q, --queue

Create message queue

-p, --mode MODE

Set permissions (octal, default 0644)

INSTALL

sudo apt install util-linux

sudo dnf install util-linux

sudo pacman -S util-linux

sudo apk add util-linux-misc

sudo zypper install util-linux

brew install util-linux

nix profile install nixpkgs#util-linux

CAVEATS

System V IPC has kernel limits on the number and size of resources. Resources are not automatically cleaned up when creating processes exit. Modern applications often prefer POSIX IPC or other mechanisms.

HISTORY

System V IPC was introduced in AT&T UNIX System V in the early 1980s. While older than POSIX alternatives, it remains widely used and supported across Unix-like systems.