Build your own shell #UN3. Tester adds unexpected "j" to input

Challenges
1

I was implementing #QP2 and while I did that i managed to break my implementation in a wierd way. Everything still works on my machine, but when the tester runs it, in stage #UN3 (and in other stages as well) it feels like appending a “j” to the input to my shell which makes the test fail. As far as I can tell, I’m not adding the “j” myself (the letter j only occurs in two lines of all my code).

[tester::#UN3] Running tests for Stage #UN3 (Redirection - Append stderr)
[tester::#UN3] [setup] export PATH=/tmp/pear/pineapple/mango:$PATH
[tester::#UN3] Running ./your_program.sh
[your-program] $ ls -1 nonexistent >> /tmp/baz/baz.mdj <-- NOTICE j HERE
[tester::#UN3] Failed to read file ("/tmp/baz/baz.md"): open /tmp/baz/baz.md: no such file or directory
----------------------------------------------------^ NOTICE LACK OF j HERE
[tester::#UN3] Assertion failed.
[tester::#UN3] Test failed

The file with the j is created btw

4

I figured it out. In order to capture tab presses I added the crossterm crate to my solution and enabled raw terminal mode, and had to implement some normal functionality myself (such as submitting input on ENTER).

The testers does not use the ENTER keycode in some of the stages to submit input, but uses CTRL+J. Which according to ChatGPT:

In Bash, pressing CTRL+J is functionally the same as pressing ENTER.

The “j” character was added because I did not handle CTRL+J case manually. It is a rather odd implementation of the testers if you ask me.

3 Likes
5

Hmm, interesting! Most users usually run into \n vs \r differences across systems. This is the first time I’ve seen Ctrl+J come up. Nice catch!

Could it be that crossterm is handling input a bit differently here? Might be worth digging into.

7

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