question about executing a bash shell script...

Hi folks, I'm learning shell scripting via linux, and have written a script that creates the core files necessary for a users website from a master set of files. Works from the shell just fine (bash makethesite.sh username pathtoputfiles pathtogetfiles) Trying to execute this via php, and it literally does nothing. If I try something like: $bashoutput=shell_exec('bash makethesite.sh username pathtoputfiles pathtogetfiles'); echo $bashoutput; I get nothing output, and the script doesn't execute. Any ideas? Kelly