[linux] Run bash command on jenkins pipeline

I'm sure that the above answers work perfectly. However, I had the difficulty of adding the double quotes as my bash lines where closer to 100. So, the following way helped me. (In a nutshell, no double quotes around each line of the shell)

Also, when I had "bash '''#!/bin/bash" within steps, I got the following error java.lang.NoSuchMethodError: No such DSL method '**bash**' found among steps

pipeline {
    agent none

    stages {

        stage ('Hello') {
            agent any

            steps {
                echo 'Hello, '

                sh '''#!/bin/bash

                    echo "Hello from bash"
                    echo "Who I'm $SHELL"
                '''
            }
        }
    }
}

The result of the above execution is