Use execvp instead of execve!

Otherwise, users of your shell will need to know the full path to execute typical commands like ls, cd, ps, etc.

The p in execvp takes only 2 parameters, but this version of exec will examine the directories in your PATH environment variable when searching for the executable file.

The execve version takes 3 parameters (execvp takes only the first 2):

1. filename
2. array of "command line" arguments
3. array of environment variable=value strings

The filename can be an absolute or relative.

For an absolute filename (one that starts with "/"), the search begins at the root directory "/" and searches through all components of the path to find the executable file.

For a relative filename (doesn't start with "/"), the search begins from the current working directory.

So with execve, you would need to type the absolute path:

 /bin/ls      
   

instead of

 ls
   

to list the current directory.