You surely are using the latest and greatest browser on your Mac. But their might be certain applications in you corporate environment that require you to use old versions of browsers. Of course you can install multiple browsers on you Mac, but having different Versions of them at hand requires a bit of fiddling some times.
I often struggled to run two different versions of Mozilla Firefox in parallel. Of course you can install an application basically in any folder on you machine and it will probably run. But applications tend to store certain app data in your “~/Library/Application Support” folder and the likes. Firefox will store it’s profile data there and some lock information when it’s running. So when you try to start a second instance of Firefox it will usually complain that another instance of Firefox is already running.
But there is a workaround using Firefox Profile support. Basically you’ll call Firefox with a certain profile because you can run multiple instances of Firefox with different profiles at the same time. Unfortunately there is no easy way to add start parameters to an Application under MacOS. But here’s the trick:
I’ve installed the latest Firefox in the default location under /Applications and let it run unmodified. I have an Firefox 3.6.x installation in my personal applications folder under ~/Applications. This one I modified to start with a certain profile. In order to achieve this, I initially called the Firefox manually invoking the Profile Manager:
Create a profile and name it “FF3″ and tick the box “Don’t ask at startup”. Now you need to tell Firefox.app to use this profile for start. In order to do this you need to modify a .plist file in the application package. That contains the start up command for Firefox. Unfortunately you can’t just add a parameter here. You need to create a shell-script that’ll call Firefox with the appropriate command. Then you’ll nominate this shell script as start command in the plist file.
So create a file named “start-firefox.sh” in ~/Applications/Firefox.app/Contents/MacOS/ with the following content:
/Users/fzurell/Applications/Firefox.app/Contents/MacOS/firefox-bin -P "FF3"
Make the shell script executable for the user: chmod u+x ~/Applications/Firefox.app/Contents/MacOS/start-firefox.sh
Then edit the file ~/Applications/Firefox.app/Contents/Info.plist
Find the key for “CFBundleExecutable”, the next line contains a string element pointing to “firefox-bin”. Replace it with your newly created shell script as seen in the screenshot and save the file.
Basically that’s all. When you now double-click the Firefox.app in your personal Application folder, it should start Firefox with the FF3 profile.
If it doesn’t your Finder cache might not yet been updated. Move the Firefox.app from the ~/Applications folder to your Desktop for a moment. Double click the Firefox.app as if you want to open it. Nothing will happen (as the shell script is pointing to ~/Applications/Firefox.app). Now move it back to ~/Applications folder. It should work now.