How to post a file version as an artifact in Jenkins

If you are using a Jenkinsfile and want to save a txt file with the build number, you just to use the $BUILD_NUMBER environment variable:

  sh 'echo "build $BUILD_NUMBER" > version.txt'

Then, in post section - always, you can post your version.txt file:

  post {

        always {

            archiveArtifacts artifacts: 'build/ , version.txt'

        }

    }

Here in the example, I am posting two files separated by commas. 

Jenkinsfile

Output