No need to worry, for most distros just run your updater, then you are safe.

How to check if you are affected, run the following code:

env x='() { :;}; echo vulnerable' bash -c "echo Your system are patched against shellshock"
 

If the output is “vulnerable” you need to update.

If the output is: “Your system are patched against shellshock” you need to do no further.

Note: Many embeded system like routers, NAS servers will be vunlnerable, please consult the company who made the device for updates.
FreeNAS 9.2.1.7 is vulnerable, but patch is comming up, restrict web interface to lan only, and if remote access is needed: make proxy and login via SSH.