How to use json variable in shell script file?

Question

I would like to use this json file to get jenkins version and java version numbers to include my script.sh file. How do we do that?

I tried {{user `java_version`}} but it did not work.

• variable.json file

  {
      "region": "us-east-1",
      "jenkins_version": "2.263.4",
      "java_version": "1.8.0"
  
  }
  

• script.sh file

  #!/bin/bash
  sudo yum update -y
  sudo yum install wget -y
  sudo yum install   java-{{user `java_version`}}-openjdk-devel -y
  sudo wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo
  sudo rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io.key
  sudo yum install -y jenkins-{{user `java_version`}}
  sudo systemctl start jenkins
  sudo systemctl status jenkins
  #Get auth password from jenkins master
  echo "authpwd="$(sudo cat /var/lib/jenkins/secrets/initialAdminPassword)
  

Answer 1

Take a look at the jq command it is a command line json parser. You can pull any field you would like.

https://www.systutorials.com/docs/linux/man/1-jq/

For example this will return the java_version number.

cat variable.json | jq .java_version

If you prefer using core commands so you don't have to install anything you can use this command.

cat input | grep java_version | awk '{print $NF}'

Shorter version of the above command before someone says you don't have to cat into grep.

grep java_version variable.json | awk '{print $NF}'

EDIT: Another option would be.

sudo yum install -y jenkins-$(grep java_version variable.json | awk '{print $NF}' | sed 's/"//g')-openjdk