Tools/scripts: Add checkuids.sh, a script to find unreferenced usernames in the UIDs file

[arrowd]

Summary

• Tools/scripts: Add checkuids.sh, a script to find unreferenced usernames in the UIDs file
• UIDs,GIDs: Cleanup unreferenced entries

Test Plan

I'm going to request an exp-run for this change once it is approved

[mat]

I don't think removing entries without checking how long they have been unused is a good idea,

If you mark an entry as free, it means it can be used again, which will most probably lead to conflicts or double entries in /etc/passwd or /etc/groups.

We don't seem to be running out of free uids and gids, a quick grep tells me we have more than 300 free in each.

[arrowd]

I don't think removing entries without checking how long they have been unused is a good idea,

And how long an entry should be unused to make viable for deletion? I doubt we have a policy for that.

If you mark an entry as free, it means it can be used again, which will most probably lead to conflicts or double entries in /etc/passwd or /etc/groups.

I checked how users/groups are created in there is indeed no check for both name and UGID.
I think the solution here would be to check both name and UGID and fail package's installation if the user/group with specified UID exists, but names do not match.
Then let the administrator clean up old entries.

We don't seem to be running out of free uids and gids, a quick grep tells me we have more than 300 free in each.

We'll have to do this sooner or later and here I am to do that. Why wait for free entries to exhaust?

[mat]

In D56578#1295345, @arrowd wrote:

I don't think removing entries without checking how long they have been unused is a good idea,

And how long an entry should be unused to make viable for deletion? I doubt we have a policy for that.

I'd say at least 10-15 years before an entry can be recycled.

We don't seem to be running out of free uids and gids, a quick grep tells me we have more than 300 free in each.

We'll have to do this sooner or later and here I am to do that. Why wait for free entries to exhaust?

I'm not convinced this solves a real problem.
I don't see this coming up as a problem in practice.
Given the existing backlog of actual framework and ports issues, I'd rather see effort directed there

[arrowd]

Given the existing backlog of actual framework and ports issues, I'd rather see effort directed there

As do I. I'd love other people to work on problems I deem important, but we're all volunteers here. What I don't do, however, is turning down contributions I personally find uninteresting.

Anyways, we can at least get the script in and maybe some UGIDs that I find to be removed 10 years ago?