Bash script to run ruby script with 2 versions of ruby and compare their outputs for diffs

pipeline-comparison.sh

#!/bin/bash

RUBY2=2.6.10
RUBY3=3.2.2

EXECUTABLE=$(basename "$0")

function usage() {
	echo "NAME
$EXECUTABLE - Compares ruby-based pipelines for submission to Buildkite

SYNOPSIS
  Usage: $EXECUTABLE PIPELINE_SCRIPT [BUILDKITE_ENV]

DESCRIPTION
  The $EXECUTABLE script runs the PIPELINE_SCRIPT with both ruby v2.6.10 and
  ruby 3.2.2, comparing the generated yaml files.

  If you haven't already loaded a Buildkite job's environment, you can pass
  the shell script's name as the BUILDKITE_ENV argument. It should export
  all env vars for the build.

	If they differ it exits with a status of 1"
}

if [ $# -lt 1 ]; then
	usage
	exit
fi

PIPELINE_SCRIPT=$1
BUILDKITE_ENV=$2

if [ -n "$BUILDKITE_ENV" ]; then
	if [ -f "$BUILDKITE_ENV" ]; then
		source $BUILDKITE_ENV
	fi
fi

for ruby_version in $RUBY2 $RUBY3; do
	RBENV_VERSION=$ruby_version ruby "$PIPELINE_SCRIPT" >"/tmp/ruby-$ruby_version.out"
done

diff /tmp/ruby-$RUBY2.out /tmp/ruby-$RUBY3.out

if [ ! "$(diff ruby-$RUBY2.out ruby-$RUBY3.out)" ]; then
	echo -e "\n\n\nThe rubies produce the same yaml"
	result=0
else
	echo -e "\n\n\nThe output differs"
	result=1
fi

exit $result