# \#UN3 recent test case mismatch in ls **URL:** \ **Category:** Challenges\ **Tags:** challenge:shell\ **Created:** [January 24, 2026, 8:16pm UTC](https://forum.codecrafters.io/t/un3-recent-test-case-mismatch-in-ls/15825 "2026-01-24T20:16:47Z")\ **Posts on this page:** 1\ **Showing post:** 27
**Author:** ![senevoldsen](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/senevoldsen/32/6460_2.png) [@senevoldsen](https://forum.codecrafters.io/u/senevoldsen)\ **Post date:** [January 25, 2026, 1:55am UTC](https://forum.codecrafters.io/t/un3-recent-test-case-mismatch-in-ls/15825/27 "2026-01-25T01:55:25Z")
The function `access` is the underlying Linux/Posix/C function to test whether we can execute. Not as in if the bit is set, but whether we might execute or not (effective vs real permissions). I don’t think there are situations where the distinction matters for the tester, and I am not sure how to achieve equivalent in Rust. About my earlier comments about `0o111` I thought mistakenly that, that was RWX and not XXX for each user, group, other. I recall another person had issue in C# when checking `0o111` and changed to only checking whether User Execute and User Read was set: [Problem locating unix executables #MG5 - #10 by salmon-571](https://forum.codecrafters.io/t/problem-locating-unix-executables-mg5/15660/10) . So I think your check here is working. I see @andy1li replicated the issue. As for the exact conditions I cannot explain. But consider this: You check whether you find the executable (using whatever condition) and get the path: `let Some(executable) = externals.get(cmd)`. Then shortly after you do `let result = match Command::new(cmd).args(args).output() {`. So `cmd=ls` and `executable=/usr/bin/ls` or something like that. But what you pass to `Command::new` is not the path but just `ls`. I can’t fathom why, but seems to me it finds a different executable than the expected one and runs. --- _[View the full topic](https://forum.codecrafters.io/t/un3-recent-test-case-mismatch-in-ls/15825)._