when I write my operating system program in c(compiled in linux,Iam unable to understand certain inbuilt functions like
1.for semaphores
    sembuf,SEM_UNDO,IPC_NOWAIT,semop(DE, ,),semptr,SHM_R,SHM_W,SETVAL, semctl(),shmget(IPC_PRIVATE,1,0666|IPC_CREAT),fork (),shmat().
     pipe()
could anyone clarify what these functions are actually meant by

u need to know the inter process communication to understand those functions. u can refer Unix manuals or Newwork Programming by Richard Stevens

Radhika yarlagadda