`$1` necessity with husky

[privatenumber]

This is more of a question than a bug report, but can be actionable depending on discussion.

The README provides instructions on how to setup commitlint with husky. I'm curious if passing in $1 is actually necessary here:

npx husky add .husky/commit-msg 'npx --no -- commitlint --edit "$1"'

Upon testing, $1 always seems to evaluate to .git/COMMIT_EDITMSG (which is also the default value for commitlint -e). Although I have read sources that say $1 evaluates to the commit message itself (rather than a file path containing it), I have not found that to be the case, which I confirmed with the Git hooks docs:

It takes a single parameter, the name of the file that holds the proposed commit log message.

Is there an edge case where $1 evaluates to a different path that this is trying to handle? Or can it be safely omitted?

---

Also, I don't think this recommended command will work in Bash because string interpolation isn't supported in single-quotes:

npx husky add .husky/commit-msg \"npx --no -- commitlint --edit '$1'\"

I'm wondering if this appears to work because it silently falls back to using .git/COMMIT_EDITMSG.

I made a test with the following commit hook to confirm:

#!/bin/sh
. "$(dirname "$0")/_/husky.sh"

echo "$1"
echo '$1'
echo $1

Result:

$ git commit -am test
.git/COMMIT_EDITMSG
$1
.git/COMMIT_EDITMSG

Is this for a specific non-Bash environment?

[escapedcat]

Hey @privatenumber good question. I'm not able to answer this unfortunately.

$1 seems to been have introduced with #2340
Maybe @Manubi knows the exact reason for this?

[privatenumber]

I found that it's safe to assume .git/COMMIT_EDITMSG as long as you're not changing the .git directory.

I investigated this behavior in the git source code here if anyone is interested:
typicode/husky#1108 (comment)