install-multi-user: fix when sudo is alias to doas

[concatime]

Motivation

In my system, sudo is a symlink to doas.
The thing is that they behave differently:

$ sudo KEY=value echo good
good
$ doas KEY=value echo bad
doas: KEY=value: command not found

The syntax of K=v before a command is only valid in a shell. But from what I understand, doas runs the command directly. So the fix is to prepend with "env":

$ doas env KEY=value echo good
good

In my case, I had HOME=/root: command not found.

Context

The fix is rather simple, so it wasn't worth to open an issue ticket.

Checklist for maintainers

Maintainers: tick if completed or explain if not relevant

• agreed on idea
• agreed on implementation strategy
• tests, as appropriate
  • functional tests - tests/**.sh
  • unit tests - src/*/tests
  • integration tests - tests/nixos/*
• documentation in the manual
• documentation in the internal API docs
• code and comments are self-explanatory
• commit message explains why the change was made
• new feature or incompatible change: updated release notes

Priorities

Add 👍 to pull requests you find important.

[abathur]

Just dot-connecting: this is either a duplicate of or would supersede:

• Fix edge case with doas in multi-user install script #4690

[concatime]

Well, I didn't see the PR you pinned. It's definitely a duplicate.

[roberth]

duplicate.

This PR is up to date and arguably more complete, fixing four instances of the problem instead of three.
That does show the fragility of the solution though, but we can solve that by testing with doas (as well as sudo of course) in CI, in tests/installer/default.nix. Could you add a new test there?