---
- name: cat resolv.conf
  telnet:
      user: "{{ foxuser }}"
      password: "{{ foxpass }}"
      login_prompt: "login:"
      prompts: "#"
      command:
          - grep 192.168.178.6  /etc/resolv.conf

  register: resolv
  changed_when: not( resolv.output | join('') | search('nameserver'))
  notify: update resolv.conf

[DEPRECATION WARNING]: Using tests as filters is deprecated. Instead of using `result|search` use `result is search`. This feature will be removed in version 2.9.

changed_when: not('nameserver' in resolv.output )

"resolv": {
    "changed": false,
    "failed": false,
    "output": [
        " grep 192.168.178.6  /etc/resolv.confrnnameserver 192.168.178.6rn[root@foxboard /root]1068#"
    ]
}

- name: cat resolv.conf
  telnet:
      user: "{{ foxuser }}"
      password: "{{ foxpass }}"
      login_prompt: "login:"
      prompts: "#"
      command:
          - grep 192.168.178.6  /etc/resolv.conf

  register: resolv
  changed_when: not ( resolv.output | join('') ) is search('nameserver')
  notify: update resolv.conf