uutils / uutils/coreutils

who: `who -b` produces no output if `/var/run/utmp` is missing

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U - who
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Rust
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Description

(This is a separate issue filed based on original-birdman's comment on #3219)


Problem

Passing -b/--boot to uutils who does not generate the same output as GNU when /var/run/utmp is missing (as is the case on Ubuntu).

Reproduce

uutils:

$ who -b
<no output>

GNU:

$ gnuwho -b
         system boot  2026-03-31 09:04
Possible fix

strace on gnuwho -b shows that it will attempt to read systemd information such as

  • /var/run/systemd/sessions/
  • /var/lib/systemd/random-seed

if /var/run/utmp is missing.

System
  • OS release: Ubuntu 26.04 (Development branch)
  • uutils coreutils version: 0.8.0 (built from main commit: f6451c7)

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

The affected entry point is the uutils who -b command; begin by tracing how it handles a missing /var/run/utmp and compare that path with GNU's behavior. Check the systemd locations named in the report, /var/run/systemd/sessions/ and /var/lib/systemd/random-seed, and reproduce the Ubuntu-like missing-utmp case. Done means who -b emits the boot time instead of no output.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
cli, operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
55/100

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