centos 7查看防火墙报错（已解决，之前安装过python3）

[root@localhost ~]# service firewalld restart
Redirecting to /bin/systemctl restart firewalld.service
Job for firewalld.service failed because the control process exited with error code. See "systemctl status firewalld.service" and "journalctl -xe" for details.
[root@localhost ~]# systemctl firewalld restart
Unknown operation 'firewalld'.
[root@localhost ~]# service firewalld stop
Redirecting to /bin/systemctl stop firewalld.service
[root@localhost ~]# service firewalld start
Redirecting to /bin/systemctl start firewalld.service
Job for firewalld.service failed because the control process exited with error code. See "systemctl status firewalld.service" and "journalctl -xe" for details.
[root@localhost ~]# systemctl status firewall
Unit firewall.service could not be found.
[root@localhost ~]# firewall-cmd --state
Traceback (most recent call last):
File "/usr/bin/firewall-cmd", line 24, in <module>
from gi.repository import GObject
ModuleNotFoundError: No module named 'gi'

以上提示中提到了“/usr/bin/firewall-cmd”，我们输入以下命令：

vim /usr/bin/firewall-cmd

修改第一行，在python后面添加数字2.7：

保存退出即可