Originally Posted by Don Cragun

What error messages did you get when you tried to compile your code? Did it complain about the symbols exexlp and prinf not being found? Did it complain about there not being any function prototypes for fork, wait, execlp, printf, exexlp, and prinf?

If you actually got an executable file named example1, why wouldn't you try executing ./example1? You showed us that you attempted to run ./first.c and there is no reason to think that a C source code file should be executable; but trying to execute it should have given you one or more diagnostic messages.

If you actually succeeded in running example1 (which, from what you have shown us, I doubt), is there an executable named yyy on your search path? Since you aren't checking the return codes on any of the functions you're calling, why would you believe that any of the functions you're calling are doing what you expected them to do?

I strongly suggest that you first get rid of all of the compilation warnings and errors in the code you're trying to compile before you try running any object file compiling it creates. Then try running the object file created; not the source file.