# Semaphore Functions

## Table of Contents

- ftok — Convert a pathname and a project identifier to a System V IPC key
- msg_get_queue — Create or attach to a message queue
- msg_queue_exists — Check whether a message queue exists
- msg_receive — Receive a message from a message queue
- msg_remove_queue — Destroy a message queue
- msg_send — Send a message to a message queue
- msg_set_queue — Set information in the message queue data structure
- msg_stat_queue — Returns information from the message queue data structure
- sem_acquire — Acquire a semaphore
- sem_get — Get a semaphore id
- sem_release — Release a semaphore
- sem_remove — Remove a semaphore
- shm_attach — Creates or open a shared memory segment
- shm_detach — Disconnects from shared memory segment
- shm_get_var — Returns a variable from shared memory
- shm_has_var — Check whether a specific entry exists
- shm_put_var — Inserts or updates a variable in shared memory
- shm_remove_var — Removes a variable from shared memory
- shm_remove — Removes shared memory from Unix systems