Jenkins 中 cd 与 dir

Jenkins file 如下：

pipeline {
    agent {label 'master'}
    stages {
        stage ('tttt') {
            steps {
                sh "pwd"
                sh "mkdir aaa"
                dir('aaa') {
                  sh "pwd"
                }
                sh "pwd"

                             echo "----------------------------"

                            sh "cd aaa"
                            sh "pwd"

            }
        }
    }
}

　dir 只改变wrap 内的路径，退出wrap,路径恢复到原来的地方

   cd 命令根本不起效！

Running on Jenkins in /applications/jenkins/workspace/ssh_test
[Pipeline] {
[Pipeline] stage
[Pipeline] { (tttt)
[Pipeline] sh
+ pwd
/applications/jenkins/workspace/ssh_test
[Pipeline] sh
+ mkdir aaa
[Pipeline] dir
Running in /applications/jenkins/workspace/ssh_test/aaa
[Pipeline] {
[Pipeline] sh
+ pwd
/applications/jenkins/workspace/ssh_test/aaa
[Pipeline] }
[Pipeline] // dir
[Pipeline] sh
+ pwd
/applications/jenkins/workspace/ssh_test

[Pipeline] echo
----------------------------
[Pipeline] sh
+ cd aaa
[Pipeline] sh
+ pwd
/applications/jenkins/workspace/ssh_test