*Shell 命令

1. 切換工作目錄到 /home/deyu1/ansible。

   [deyu1@kvm19 ~]$ cd ansible/
   

2. 執行 ansible ad-hoc 命令，將群組 dev 的主機重開機，出現錯誤。

   [deyu1@kvm19 ansible]$ ansible dev -a "/sbin/reboot"
   kvm11 | FAILED | rc=1 >>
   Failed to set wall message, ignoring: Interactive authentication required.
   Failed to reboot system via logind: Interactive authentication required.
   Failed to open initctl fifo: Permission denied
   Failed to talk to init daemon.non-zero return code
   

3. 執行 ansible ad-hoc 命令，sudo 將群組 dev 的主機重開機，成功執行，出現的錯誤訊息是因關機時 ssh 無法連線。

   [deyu1@kvm19 ansible]$ ansible dev -a "sudo /sbin/reboot"
   kvm11 | UNREACHABLE! => {
       "changed": false,
       "msg": "Failed to connect to the host via ssh: Shared connection to 
   kvm11 closed.",
       "unreachable": true
   }
   

4. 群組 prod 有 kvm13 及 kvm14 兩台主機都成功重開機，出現的錯誤訊息是因關機時 ssh 無法連線。

   [deyu1@kvm19 ansible]$ ansible prod -a "sudo /sbin/reboot"
   kvm13 | FAILED | rc=-1 >>
   Failed to connect to the host via ssh: ssh: connect to host kvm13
    port 22: Connection refused
   kvm14 | FAILED | rc=-1 >>
   Failed to connect to the host via ssh: ssh: connect to host kvm14
    port 22: Connection refused
   

5. ansible 執行時會同時開啟多個 bash 子程式同步執行，預設數量是 5。

   [deyu1@kvm19 ansible]$ grep forks /etc/ansible/ansible.cfg 
   #forks          = 5
   

6. 如果群組的主機很多，可使用選項 -f 指定 bash 子程式數量同時執行，以下是同時開啟 10 個 bash，將受管主機重開機。

   [deyu1@kvm19 ansible]$ ansible prod -a "sudo /sbin/reboot" -f 10
   

7. -u root 指定以用戶 root 執行命令，因為 deyu1 無法免密碼 ssh 連線 kvm11 的 root 用戶，所以出現無法連線的訊息。

   [deyu1@kvm19 ansible]$ ansible dev -a "/sbin/reboot" -u root
   kvm11 | UNREACHABLE! => {
       "changed": false,
       "msg": "Failed to connect to the host via ssh: root@kvm11:
    Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).",
       "unreachable": true
   }
   

8. --ask-pass 要求輸入連線密碼，輸入後成功重新啟動 kvm11，出現的訊息一樣是因關機 ssh 連線中斷。

   [deyu1@kvm19 ansible]$ ansible dev -a "/sbin/reboot" -u root --ask-pass
   SSH password: 
   kvm11 | FAILED | rc=-1 >>
   Failed to connect to the host via ssh: ssh: connect to host kvm11
    port 22: Connection reset by peer