---
- hosts: all

  tasks:

    - name: test1
      debug:
        msg: "test1"

    - name: test2
      shell: cat /etc/redhat-release

    # .rc 在这里是固定用法表示 return code
    - name: Report 'changed' when the return code is not equal to 0
      shell: cat /etc/redhat-release
      register: my_result
      changed_when: "my_result.rc != 0"

    - name: add ok.txt
      copy:
        content: 'service ok'
        dest: /tmp/ok.txt

    - name: add error.txt
      copy:
        content: 'service error'
        dest: /tmp/error.txt

    - name: test3
      shell: cat /tmp/error.txt

    - name: test4
      shell: cat /tmp/error.txt
      register: my_result
      failed_when: "'error' in my_result.stdout"

    - name: test5
      shell: cat /tmp/ok.txt
      register: my_result
      failed_when: "'error' in my_result.stdout"


# ansible-playbook main1.yml