what might be the reasons of my output missing one line after clearn : 
main : linked_list.o main.o

           gcc -
    Wall - g - std = gnu99 -
                     o main linked_list.o main
                         .o

                             main.o : linked_list.h

                                          gcc -
                     Wall - g - std = gnu99 -
                                      c main
                                          .c

                                              linked_list.o
    : linked_list.c linked_list.h

          gcc - Wall - g - std = gnu99 -
                                 c linked_list.c

                                     clean : rm -
                                 f linked_list.o

                                     rm -
                                 f main.o
