如何在Jenkinsfile groovy中验证grep的输出

def grepOutput = sh(script: 'grep "keyword" file.txt', returnStdout: true).trim()

assert grepOutput.contains("expected output")

pipeline {
    agent any
    
    stages {
        stage('Verify Grep Output') {
            steps {
                script {
                    def grepOutput = sh(script: 'grep "keyword" file.txt', returnStdout: true).trim()
                    assert grepOutput.contains("expected output")
                }
            }
        }
    }
}