Just to amplify on Monk::Thomas's reply, the reason you need to put a ./ in front of commands run in the current directory, is to prevent the system from searching your system PATH first. What if the file name was identical to something else in your PATH? It gets confusing and is a security hazard, so the rule is put ./ in front of any command run from the current working directory. I hope it helps you remember it, it becomes second nature after awhile. :-)