how a stray "j" ruined my evening — napkins

← back 2026-06-08

Some time ago I decided to wrangle a silly link shortener that I called shirts linkener, shirts for short.

There's nothing special about it in particular, rather it's in my `run-once-forget-forever` shell script that copies the generated links to a clipboard using `wl-clipboard`.

#!/bin/sh
shirt=$(curl -s -X POST "$(pass show shirts/url)" \
    -H "Authorization: Bearer $(pass show shirts)" \
    -H "Content-Type: application/json" \
    -d "{\"url\": \"${1?missing url}\"}")
echo "$shirt" | jq
echo "$shirt" | jq -r '.short_url' | wl-copy

Nothing out of the ordinary here. It shortens the link and copies it to a clipboard. By then I have been hapilly using it for couple of months without an issue.

The fun began when I decided to try out `gurk`, a Signal TUI written in Rust. Those who know me, know my obsession with terminal interfaces so this was an obvious match.

One evening I was sharing a link to an image hosted on S3 when I noticed people were saying it shows 404 to them.

After pasting the link into Firefox, it worked. What is going on? I send them the link and it works now...

Time passes and I get the same responses from multiple friends - 404. After some time looking at the messages I notice a pattern - each url ends with "j".

Turns out I was copying the link with a `\n` at the end, which in most cases went unnoticed, but in ANSI newline delimiter is translated as "j", hence the stray jay at the end of each link.

After having a solid five minutes of immense shame I found that `jq` has `--join-output` argument, which prevents exactly my case:

--join-output / -j:
            Like -r but jq won't print a newline after each output.

Moral of this story is that terminals are fun and shooting myself in the foot repeatedly acts as a great learning opportunity.

Some of the sources around control codes and escape sequences.

• <https://gist.github.com/fnky/458719343aabd01cfb17a3a4f7296797>
• <https://cirw.in/blog/bracketed-paste>
• <https://jdhao.github.io/2021/02/01/bracketed%5Fpaste%5Fmode>

m.