Linux

I am writing a software product and hope that it will work on a variety of Linux distributions. At the moment, I am trying to create some kind of Linux version of patches/upgrades of installed software. Gathering information on available updates isn't hard, nor is installation of updates, but I can find no coherent scheme for rolling an update back without uninstalling the application altogether.

I cannot find a way to do it for Redhat, Debian or any other family of Linux - at least I cannot find a way which isn't peculiar to just a few versions, and isn't obsolete or slated for retirement.

The method cannot be manual, I need to do it from a program, and it cannot depend on an esoteric utility which many of my customers won't have.

Does anyone have any ideas of how to do this for Redhat, or Debian, or SuSe, or any major distribution?

Thanks in advance.

Brandon

They are not updates. They are packages. You can make things work outside of a package via a series of scripts, however.

A package is an update if it updates an earlier version of the same software.

What would these scripts do?

You don't need a previous version installed to install a newer one.

So, they're still not 'updates'. They're not small changes to a large thing, they're drop-in replacements for the whole.

That's what makes 'rollback' difficult. You need to enumerate the differences between them yourself, decide which are important, which aren't, which are defaults that probably shouldn't be reinstalled overtop of the existing ones, etc, etc. It might be possible to simply uninstall it and reinstall the old. It might not. There might be dependencies and dependency changes involved in that, too.

Hi, Corona.

I also have to consider the possibility that the customer is trying it on basic, necessary software, so I would rather not uninstall and re-install in case something went wrong. They wouldn't like it if I wrecked the customer's system. I was hoping that someone had already worked out a system to do it, at least for some Linux family. I hate to concede defeat, but, at the same, time, I am probably not in a position to concoct a mammoth scheme for saving all necessary info on every update within my software. No one has ever solved this problem in a coherent way?

You are looking at rebuilding the world. Inside a package are a series of files and scripts.

Your package can work in several ways. You can inventory all the files owned by your application, save them to a directory based on the version, and then lay down the new files, however this may upset some customers when you use disk space they otherwise would not want, so you can make this step optional, but realize the stupider customers will screw it up.

Otherwise, you can use a simpler method than rpm or deb files, like a .tgz file that unpacks the changes, but also realize, there is more work, and getting versions is trickier this way.

Many customers have systems by which to load/remove software. You want a fits all solution and they don't exist. It will involve you documenting lots of things, and scripting many others yourself.

You could always try keeping backups.