freebsd man page for sem

SEM(4)							   BSD Kernel Interfaces Manual 						    SEM(4)

NAME
     sem -- POSIX semaphores

SYNOPSIS
     To compile this driver into the kernel, place the following line in your kernel configuration file:

	   options P1003_1B_SEMAPHORES

     Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

	   sem_load="YES"

     To load the driver as a module at run-time, run the following command as root:

	   kldload sem

DESCRIPTION
     The sem facility provides system calls used by the standard C library (libc) to implement POSIX semaphores.  This facility offers support for
     such functions as sem_init() and sem_wait().  It is available both as a kernel option for static inclusion and as a dynamic kernel module.

SEE ALSO
     sem_destroy(3), sem_getvalue(3), sem_init(3), sem_open(3), sem_post(3), sem_wait(3), config(8), kldload(8), kldunload(8)

HISTORY
     The sem facility appeared in FreeBSD 5.0.

BSD
								 February 7, 2014							       BSD