Quick swap out of operating system?

[4C4Blessed]

Hello,

I've installed a program that has corrupted some parts of my operating system (trust me, it is broken and broken good). I've done all of the usual fix-its and nothing works. I do not want to "re install" the whole operating system using the install DVD. I have a perfectly good installation of the operating system sitting on an external firewire drive - my emergency drive. That external drive boots up, no problems. It contains all of my third party system extensions and whatnot already installed on it on the system level and ready to go.

I want to copy that operating system over from the external drive to my internal drive. I don't need or want to copy user accounts, applications, or anything else. Just the operating system, and only the operating system. The whole operating system, intact, functioning, and ready to boot. Hopefully, all in one go.

I'm familiar with asr from the terminal, but that wipes the whole drive (this is bad) and copies everything (also bad). Which is of course exactly what I do not want to happen. Unless there are some additional commands for asr?

For example, in the days of old, you could simply delete the System Folder, and then drag a fresh one over. Bless it, then it works. Simple. No if's, and's, or but's. No kinda's, sorta's or maybe's. It just worked. I need to accomplish this same feat but with OSX now, somehow.

Thanks a bunch!

[Giaguara]

I guess you could do the usual *x backup using rsync but syncing only the system and not your user data.
But it'd make more sense to copy all the data that you want to keep and then do erase and install on that system, and bring all data over except the program which caused that mess.

[Mikuro]

I recommend manually moving all the 'old' system items into a backup folder (just in case), then using a tool like Carbon Copy Cloner to copy the system files from your FW drive. CCC is designed to take care of all the dark magicks required for blessing an OS X volume. It's served me well in the past. I've used it to copy system files without user files and apps many times.

Edit: Naturally, you should back up your data first. Just in case.

[4C4Blessed]

Great suggestions. I've look into them. Thanks so much!! :-D