GitHub Actions · Ubuntu 26.04 · Checked November 4, 2026

"coreutils: unknown program" on ubuntu-latest (Ubuntu 26.04): uutils, the Rust coreutils

ubuntu-latest is moving from Ubuntu 24.04 to 26.04 between October 19 and November 19, 2026 (what else changes). On 26.04, most of the core tools (sleep, ls, cat, timeout and the rest) come from uutils, a Rust rewrite of GNU coreutils. Scripts and tests that relied on GNU's behavior break in a few ways, and the most common message is this one:

coreutils: unknown program 'codex'

A renamed copy of sleep

uutils ships one program for all the tools, and it decides which tool to be from the name it was called by. Tests often fake a long-running process by copying or linking sleep under another name, so that pgrep can find it. On 26.04 that copy exits at once (pithead #3783, crewship #4062):

coreutils: unknown program 'p2pool'

The test then fails somewhere else, waiting for a process that is already gone. A name that ends in the tool's name, such as fake-sleep, still works, because uutils matches the end of the name. Two fixes that work on both images:

Link or copy GNU's sleep, which does not care about its name. 26.04 installs it as gnusleep; 24.04 has only sleep, which is GNU's there:
```
ln -s "$(command -v gnusleep || command -v sleep)" "$dir/codex"
```
Make the fake a small script. Linux names a script's process after the script, so pgrep -x still finds it (spicetify #4049):
```
#!/bin/sh
sleep 600
```

timeout -k does not kill the whole process group

uutils timeout sends the first signal to the command's process group, as GNU does, but the KILL from -k or -s KILL goes only to the direct child (uutils #15768, open). Anything the command started keeps running: a step that used timeout -k to stop a stuck install now waits, and a test that expected the kill fails with its own timeout (openRepoTools #297). Use GNU's timeout, which 26.04 installs as gnutimeout (waitron #2400 does this):

T=$(command -v gnutimeout || command -v timeout)
"$T" -k 10 300 ./install.sh

Other differences seen in CI

cat and echo given a closed standard input or output can exit 0 where GNU's exit 1, so tests about closed descriptors fail (blairham/sh #7199).
mkfifo refuses a file name that is not valid UTF-8: error: invalid UTF-8 was detected in one or more arguments (proton-drive-sync-engine #509).
Not every tool is uutils. On a 26.04 runner, /usr/bin/cp and /usr/bin/mv point to GNU's gnucp and gnumv, while /usr/bin/ls points into /usr/lib/cargo/bin/coreutils/. A test that resolves links and expects the path to end in cp fails (kiwi #1479).

To see which one a step got, ask the tool. On 26.04, timeout --version prints timeout (uutils coreutils) 0.10.0, and readlink -f "$(command -v sleep)" shows where the name points.

GNU's tools are still there

On 26.04 the coreutils package depends on coreutils-from-uutils, which depends on gnu-coreutils, so GNU's tools are always installed with a gnu prefix: gnusleep, gnutimeout, gnucat, gnudate, gnusort, gnutail and the rest. That is the smallest fix for one command. In an image you build from ubuntu:26.04, you can switch the whole set back, as some projects do in their Dockerfiles (kickstart-flavor-php #4):

apt-get install -y --allow-remove-essential coreutils-from-gnu coreutils-from-uutils-

Or pin the job with runs-on: ubuntu-24.04 until the scripts are fixed; it holds until GitHub retires 24.04. Either way, look at "Set up job": the Runner Image group says ubuntu-26.04 or ubuntu-24.04. A re-run can land on 24.04 and pass until November 19, so a green re-run proves nothing.

Other 26.04 failures

bubblewrap on Ubuntu 26.04: a sandbox inside bwrap fails under AppArmor's bwrap-userns-restrict.
sudo -E on Ubuntu 26.04: sudo is sudo-rs, which ignores -E.
apt on Ubuntu 26.04: renamed and removed packages.
Playwright on Ubuntu 26.04: versions before 1.61.0 fail to install.

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