Argument

 

name

   a string naming the semaphore object.
 

ooption

   Specifies whether the semaphore is to be created (O_CREAT option
   bit set) or only opened (O_CREAT option bit clear). If O_CREAT is
   set, the O_EXCL option bit may additionally be set to specify
   that the call should fail if a semaphore of the same name
   already exists. The O_CREAT and O_EXCL options are defined in
   the <fcntl.h> header file.
 

mode

   The semaphore's permission bits. This argument is used only when
   the semaphore is being created.
 

value

   The initial value to be given to the semaphore. This argument is
   used only when the semaphore is being created.