semget

semget key, nsems, size, flags

• Calls the System V IPC system call semget(2). The function returns the semaphore ID, or the undefined value if there is an error. On error, it puts the error code into $!. Before calling, you should say:
  
  

  require "ipc.ph"; require "sem.ph";
  

  
  
  This function is available only on machines supporting System V IPC.