docker run -p 8080:8080 -p 50000:50000 -v /Users/XXXi/jenkins_home:/var/jenkins_home jenkins
在 Environment variabless 设置了环境变量
PYTHON3 
编写 pipeline
pipeline {
    agent any
    stages {
        stage('build') {
            steps {
                sh '${PYTHON3}/bin/python3 --version'
                echo 'python~~~~'
            }
        }
    }
     post {
        always {
            echo 'report'
        }
    }
}
/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6/bin//python3: not found