Ios 6.1.2 Jailbroken to ios7?

I have tried to update a jailbroken iphone 3gs before and it bricked the phone, what will happen if update my iphone 4s ios 6.1.2 jailbroken to ios 7?

You will need to back up your iPhone (well, you do not need to), then restore from backup once you restore completely your iPhone to iOS 7.1.2.

You can't update a jailbroken iPhone. You have to restore it, or put it in dfu or recovery mode and go on from there. (look it up its simple)

Well you'd have to restore your iPhone 4S (through iTunes) then update it to the latest ios (which is currently ios 7.12).

Do NOT update directly from the settings, that bricks Jailbroken devices.

The only way to update safely is through iTunes on a computer.