README.md

When directive

pipeline {
    agent any
    environment{
        abc = "HELLO"
    }
    stages {
        stage('one') {
            when {
                environment name: 'abc', value : 'HELLO'
            }
            steps {
                echo 'HELLO there!!'
            }
        }
    }
}

pipeline {
    agent any
    environment{
        abc = "HELLO"
        efg = "HI"
    }
    stages {
        stage('one') {
            when {
                anyOf{
                    environment name: 'abc', value : 'HELLO'
                    environment name: 'efg', value : 'KAMAL'
                }
            }
            steps {
                echo 'HELLO there!!'
            }
        }
    }
}

NOTE: Please go through all the options we have with "when" block at least once.
https://www.jenkins.io/doc/book/pipeline/syntax/#when