Functions in this library provide most of the interfaces specified by the POSIX.1b Realtime Extension. See standards(5). Specifically, this includes the interfaces defined under the Asynchronous I/O, Message Passing, Process Scheduling, Realtime Signals Extension, Semaphores,
Shared Memory Objects, Synchronized I/O, and Timers options. The interfaces defined under the Memory Mapped Files, Process Memory Locking, and Range Memory Locking options are provided in libc(3LIB).
See the man pages for the individual interfaces in section 3RT for information on required headers.
The name libposix4 is maintained for backward compatibility and should be avoided. librt is the preferred name for this library.