can not create file via Groovy code(or java code) in jenkinsfile of a pipeline job on Jenkins

Question

pipeline {
    agent any

    stages {
        stage(\'Build\') {
            steps {
                echo \'Building..\'
                echo \"whoami\".execute().t         


        

Answer 1

This is due to Jenkins not implementing Groovy itself but an interpreter (CPS) - https://github.com/cloudbees/groovy-cps

To help deal with the complexities introduced, there are some common Steps implemented to take the trouble out of tasks such as creating a file.

To use Jenkins pipeline steps out of the box, use writeFile: https://jenkins.io/doc/pipeline/steps/workflow-basic-steps/#code-writefile-code-write-file-to-workspace

writeFile([file: 'file.txt', text: filetxt])

If your deadset on writing your own, I suggest splitting it out into a Shared library, note this will probably cause ScriptSecurity alerts that will require approval:

final class PipelineUtils implements Serializable {
    private script=null
    private static final PipelineUtils instance = new PipelineUtils()
    @NonCPS
    String saveFile(String filename, String text) {
        String PWD = script.pwd()
        String filePath = "${PWD}/${filename}"

        File file = new File(filePath)
        file.text = text
    }
}

See https://github.com/jenkinsci/pipeline-plugin/blob/master/TUTORIAL.md for information regarding @NonCPS and nonserializable objects.