i get this error

Which error is that then? 'source' is a built-in to csh or bash to read and execute a file without creating a child process, 'pwd' is a built-in shell command, so I'm not surprised you get an error. What is it you are trying to do? If you want to get the current working directory use Cwd.

Using another program, like a shell, to do simple stuff like that is like employing someone else to tie your shoe laces - expensive and slow.