If you've gotten a jailbroken copy of iOS 4.2 running on your iDevice, you've probably discovered that Cydia has stopped running on said iDevice. Bummer. There is a Cydia update in the pipeline, but until it makes its public debut, here's a workaround to "re-Cydiavate" in the interim:
- Start with a jailbroken copy of iOS 4.2/4.2.1 GM. Haven't jailbroken it yet? For crying out loud, why not? Our articles How To: Jailbreak iOS 4.2.1 GM on iPhone and iPod Touch With Redsn0w and How To: Jailbreak iPad 4.2 GM With PwnageTool are great places to start. Also, make sure your device is SSH enabled.
- Fire up the Terminal app in OS X and type:
apt-get install bsdiff
- Download the Cydia.patch for iOS 4.2.1. Copy it to /Applications/Cydia.app/Cydia_ by SSH‚Äôing into your iOS device:
cp Cydia_ Cydia.bak
bspatch Cydia.bak Cydia_ Cydia.patch
chmod +x+s /Applications/Cydia.app/Cydia_
Congratulations! You're now the proud owner of an untethered, jailbroken iOS 4.2.1 device with full Cydia functionality. That wasn't so hard now, was it?