Dup() ve Dup(2) Çagrısı Nedir?

//BİR PROESİN CIKTISINI KOPYALAMAYA YARAR DUP()...YÖNLENDİRMEYE YARAR..İKİ ÇEŞİTTİR
//İstersek Tanıtıcıyı  Kapatırız Kapatmasakta OLur..FAKAT DUP2 İLE ESKİ TANITICI(fd) KAPATILIR 







KULANIMI:


SYSTEM CALL: dup();                                                           

  PROTOTYPE: int dup( int oldfd );                                              
    RETURNS: new descriptor on success                                          
             -1 on error: errno = EBADF (oldfd is not a valid descriptor)       
                                  EBADF (newfd is out of range)                 
                                  EMFILE (too many descriptors for the process) 









childpid = fork();
       
       if(childpid == 0)
       {
               /* Close up standard input of the child */
               close(0);
               
               /* Duplicate the input side of pipe to stdin */
               dup(fd[0]);
               execlp("sort", "sort", NULL);
               .
       }




//BUDA DİGER ŞEKLİ KULANIMI :DUP2()

SYSTEM CALL: dup2();                                                          

  PROTOTYPE: int dup2( int oldfd, int newfd );                                  
    RETURNS: new descriptor on success                                          
             -1 on error: errno = EBADF (oldfd is not a valid descriptor)       
                                  EBADF (newfd is out of range)                 
                                  EMFILE (too many descriptors for the process) 

  NOTES: the old descriptor is closed with dup2()!












childpid = fork();
       
       if(childpid == 0)
       {
               /* Close stdin, duplicate the input side of pipe to stdin */
               dup2(0, fd[0]);
               execlp("sort", "sort", NULL);
               .
               .
       }