How to use bash variables in Jenkins multi-line shell script - bash

Question

I have unsuccessfully tried to use bash variables in Jenkins pipeline.
My first attempt
sh """#!/bin/bash
for file in *.map; do
filename=`basename $file .map`
echo "##### uploading ${$filename}"
curl -X POST ${SERVER_URL}/assets/v1/sourcemaps \
-F service_name="${SERVICE_NAME}" \
-F service_version="${revision}" \
-F bundle_filepath="${main_url}${filename}" \
-F sourcemap="#${filename}.map" &
done
wait
"""
Resulted in exception: MissingPropertyException: No such property: file
The second attempt, after seeing this answer https://stackoverflow.com/a/35047530/9590251
sh """#!/bin/bash
for file in *.map; do
filename=`basename \$file .map`
echo "##### uploading \$filename"
curl -X POST ${SERVER_URL}/assets/v1/sourcemaps \
-F service_name="${SERVICE_NAME}" \
-F service_version="${revision}" \
-F bundle_filepath="${main_url}\$filename" \
-F sourcemap="#\$filename.map" &
done
wait
"""
Simply omitted bash variables. So $filename was empty.
How do I need to property encode bash variables in this scenario?

Answer 1

Try this:
sh """#!/bin/bash
set -x
for file in *.map; do
filename="\$(basename "\$file" .map)"
echo "Uploading \$filename"
curl -X POST "${SERVER_URL}/assets/v1/sourcemaps" \
-F service_name="${SERVICE_NAME}" \
-F service_version="${revision}" \
-F bundle_filepath="${main_url}\$filename" \
-F sourcemap="#\${filename}.map" &
done
wait
"""