Partition /usr/local : Can I use the software there after reinstall?

Question

I want to reinstall Linux OS, and before that, I think I will partition my hard disk again. (I just use a simple one partition / for root, and make Linux automatically put all other directories there).

I often save software installations in /usr/local. So, my question is: suppose I create a new partition, /usr/local, and save data there; if I reinstall Linux again, can I continue to use this software and not need to install again?

I'm new to Linux World, so I'm not sure of these things.

Answer 1

My suggestion on this was, make a backup of whole root fs (including /usr/local), then re-partition, mount all partition, and extract everything.

After that all your files would stand, and your disk got re-partitioned.

If you simply backup /usr/local, there's a risk that once your system libraries get updated, those software (non-static ones) might need re-linking.

Answer 2

You use both the phrase data and software. Generally,

1. you can save data (files you created)
2. you have to re-install software

If you download and compiled your own packages, and you put everything for them in /usr/local, then yes, you can probably save the software as well. But if you link them against shared libraries, you may still have issues if those libraries are outside of /usr/local and change when you re-install.

If you install software using your distributions package manager then you're probably going to need to re-install those packages, but you can save data in any partition you don't format.

Answer 3

If you partition your disk, you'll loose everything in /usr/local.

As to the real question, you certainly can continue using the software in usr/local. But be aware that your package manager doesn't know about it, and can very well update (or even delete) packages that something in /usr/local needs, and so it can stop working at any time.