Build a JSON string with Bash variables

Question

I need to read these bash variables into my JSON string and I am not familiar with bash. any help is appreciated.

#!/bin/sh

BUCKET_NAME=testbucket
OBJECT_N         


        

Answer 1

To build upon Hao's answer using NodeJS: you can split up the lines, and use the -p option which saves having to use console.log.

JSON_STRING=$(node -pe "
  JSON.stringify({
    bucketname: process.env.BUCKET_NAME,
    objectname: process.env.OBJECT_NAME,
    targetlocation: process.env.TARGET_LOCATION
  });
")

An inconvenience is that you need to export the variables beforehand, i.e.

export BUCKET_NAME=testbucket
# etc.

---

Note: You might be thinking, why use process.env? Why not just use single quotes and have bucketname: '$BUCKET_NAME', etc so bash inserts the variables? The reason is that using process.env is safer - if you don't have control over the contents of $TARGET_LOCATION it could inject JavaScript into your node command and do malicious things (by closing the single quote, e.g. the $TARGET_LOCATION string contents could be '}); /* Here I can run commands to delete files! */; console.log({'a': 'b. On the other hand, process.env takes care of sanitising the input.