Having trouble accessing the arguments to the git pre-receive hook

I am running vanilla git (git version 2.23.3) as origin master of a bare repository on an AWS instance.

I have created a file repo_dir/hooks/pre-receive with the following contents:

#!/bin/bash -p

echo $1 > pre-receive-old-hash.txt
echo $2 > pre-receive-new-hash.txt
echo $3 > pre-receive-ref.txt

exit 1

I make a test push from my remote. I can confirm that hook is run, as I get the push rejected.

However, while the pre-receive-x.txt files exist, they are empty. What am I doing wrong?

>Solution :

https://git-scm.com/docs/githooks#pre-receive

It takes no arguments, but for each ref to be updated it receives on standard input a line of the format:

<old-value> SP <new-value> SP <ref-name> LF

(Emphasize mine — phd)

Make your script this:

#!/bin/bash -p

while read old new refname; do
    echo $old >> pre-receive-old-hash.txt
    echo $new >> pre-receive-new-hash.txt
    echo $refname >> pre-receive-ref.txt
done

exit 1