What Is Interprocess Communication?

Interprocess communication allows processes to synchronize with each other and exchange data. In general, System V (SysV) IPC facilities provide three types of resources:

• Semaphores. Allow processes to synchronize with other and also prevent collisions when multiple processes are sharing resources.

• Message queues. Asynchronously pass small data, such as messages, between processes.

• Shared memory segments. Provide a fast way for processes to share relatively large amounts of data by sharing a common segment of memory among multiple processes.

In addition to these resources, IPC pipes and FIFOs are among the most commonly used IPC facilities in UNIX-based systems:

• Pipes are unidirectional, first-in/first-out data channels that pass unstructured data streams between related processes.

• FIFOs (a.k.a. named pipes) are pipes that have a persistent name associated with them.

The next section looks at interprocess communication resources and the command that returns information about those resources.