gistfile1.txt

pipeline {
    agent label:'master'
    stages {
       stage('build') {
          execute 'echo step1'
          execute 'echo step2'
          execute '''
             echo 'Multiline'
             echo 'Example'
          '''
          execute 'not using shell'
       }
    }
}

execute is something like

if(platform == windows)
 bat command
 else 
 sh command