Can you "re-install" an application with Time Machine?

I've been using my iMac for almost a year now, and I'm still learning the differences between a mac and a pc. A couple of days ago one of my applications was unable to update and I tried deleting it and reinstalling from Time Machine when I knew it was working right. When I went to run the app it said I was missing some files.

So my questions are; (a) can you use time machine to re-install a program from say a month ago or so? And (b) if you are going to re-install any software, do you simply put the program in the trash and then reinstall from the CD?

And of course, tell me if Time Machine has limitations that should be observed with regard to what you can recover, and also... is there possibly some corrupted files in a "registry" (remember I'm from the PC world recently) that would screw up my re-install?

Many apps for OS X come in a self-contained package that looks like a single file. These don't need an installer because they can be run from anywhere and will install any support files they may need automatically to the appropriate place in the Library. You just drop the package yourself into the Apps folder and run it. Done. It doesn't really matter if you get the app from the Internet or the Time Machine.

However there are some apps that still rely on an Installer to copy various files to the appropriate places in your system. In such cases, merely recovering the app that goes in the Apps folder isn't enough. You'd have to also recover all the extra files installed by the Installer. In such a case, you are better off just reinstalling from scratch.

lifeisabeach said:

In such cases, merely recovering the app that goes in the Apps folder isn't enough. You'd have to also recover all the extra files installed by the Installer. In such a case, you are better off just reinstalling from scratch.

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Aha... that's what I thought. So, if I place whatever is left over on my machine into the trash, will that erase all history so that when I put the CD back in, it'll install properly and not be looking at any residue from the previous install?

I can see the value of Time Machine to recover a picture or document, but I get a sense that it does have some limitations. I originally thought of it as a "restore to DD/MM/YYYY" and everything would be right back where it was three weeks ago if that was the selected date.

drgrafix said:

Aha... that's what I thought. So, if I place whatever is left over on my machine into the trash, will that erase all history so that when I put the CD back in, it'll install properly and not be looking at any residue from the previous install?

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Not all "residue" will be removed unless you use an application like AppCleaner or AppZapper. That said, this "residue" should not prevent you from reinstalling the application.

drgrafix said:

Aha... that's what I thought. So, if I place whatever is left over on my machine into the trash, will that erase all history so that when I put the CD back in, it'll install properly and not be looking at any residue from the previous install?

Click to expand...

I'm not quite sure what you mean here. If you need to reinstall an app, just reinstall it. Whatever "residue" there may be should be irrelevant... it should just overwrite it.

I can see the value of Time Machine to recover a picture or document, but I get a sense that it does have some limitations. I originally thought of it as a "restore to DD/MM/YYYY" and everything would be right back where it was three weeks ago if that was the selected date.

Click to expand...

Well if you set the Time Machine to back up EVERYTHING, then yeah, you could restore the system back completely to a specific date by simply choosing the root folders and telling it to restore them all. But that would be an incredible waste of drive space to archive multiple copies of your system when certain apps and system files can more easily be reinstalled from the original source.