How to get exec() to display output from UNIX Shell Environemnt?

Hi! How do I get the php function exec() to spit out the data from the Unix Shell Environment onto the webpage? I mean, I can create a script in bash shell environment using the terminal on the Unix machine and it would spit out the background information from the O/S along with the shell script. I can do that with cURL. So, for the PHP, I would need to use exec() but it only executed the script without a problem but no shell output from the unix shell onto the webpage. How can I do that? It is very helpful for troubleshooting purpose. Thanks, Scott F.