The Linux Programming Interface

51INTRODUCTION TO POSIX IPC

The POSIX.1b realtime extensions defined a set of IPC mechanisms that are analogous to the System V IPC mechanisms described in Chapters 45 to 48. (One of the POSIX.1b developers’ aims was to devise a set of IPC mechanisms that did not suffer the deficiencies of the System V IPC facilities.) These IPC mechanisms are collectively referred to as POSIX IPC. The three POSIX IPC mechanisms are the following:

• Message queues can be used to pass messages between processes. As with System V message queues, message boundaries are preserved, so that readers and writers communicate in units of messages (as opposed to the undelimited byte stream provided by a pipe). POSIX message queues permit each message to be assigned a priority, ...