shell w/gphoto2 and Powershot G7

Hello,
I have a question regarding the “shell” object and terminal commands.
I’m using “gphoto2″ library with terminal to remotely control a Canon Powershot G7.
http://www.gphoto.org/
When using basic gphoto2 commands such as “gphoto2 –list-ports ” in shell, it doesn’t work?
The same command and various others work in terminal? I assume it’s a syntax thing?
Any insight would be greatly appreciated!
Stuart