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
.
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.