Arguments

 

file_desc

   An open file descriptor obtained from a successful open, fcntl,
   or pipe function.
 

request

   The operation to be performed.
 

arg

   A variable that depends on the value of the request argument.

   For a request of F_DUPFD, F_SETFD, or F_SETFL, specify arg as an
   int.

   For a request of F_GETFD and F_GETFL, do not specify arg.

   For a request of F_GETLK, F_SETLK, or F_SETLKW specify arg as a
   pointer to a flock structure.