title: Add directory to the PATH for execvp()
body: <p>I am writing a small console-like program in C, along with implementations for ls, tac and dir.</p>
  
  <p>I use execvp() function to override the forked children of the process, but when the user inserts one of the above 3 commands, I have to execute my own version, not the one from the system.</p>
  
  <p>I know that execvp() uses the system PATH variable to search in different locations for the executable file. Can I somehow edit the PATH in my program, so I could add a custom directory as the first place for execvp() search?</p>
  
  <p>Thank you!</p>