Get last commit changed files in Jenkins Pipeline

To get all the modified files when starting a Jenkins Pipeline, you've just have to do 2 steps.

1. Add to the end of your scripted pipeline the following function:

 @NonCPS
def getChangedFilesList() {

    changedFiles = []

    for (changeLogSet in currentBuild.changeSets) {

        for (entry in changeLogSet.getItems()) { //for each commit in detected changes

            for (file in entry.getAffectedFiles()) {

                if (!changedFiles.contains(file.getPath())) { // do not add duplicates
                    changedFiles.add(file.getPath()) 
                }
            }
        }
    }

    return changedFiles
}

2. Call the function in a stage, after cloning the repo of your source code, to get the list of changed files (with their relative paths):

stage('Check environment') {

    steps {
        script {
            modified_files = getChangedFilesList()
            if ("myfile.txt" in modified_files) {
                echo "The file has been changed"
            } else {
                echo "The file has not been changed"
            }
        }
    }
}

That's all!