常见问题
1. root用户无法修改hosts文件
root@VM-16-14-debian:/etc# sudo chmod u+w hosts
sudo: unable to resolve host VM-16-14-debian: Name or service not known
chmod: changing permissions of 'hosts': Operation not permitted
root@VM-16-14-debian:/etc# chmod u+w hosts
chmod: changing permissions of 'hosts': Operation not permitted
root@VM-16-14-debian:/etc# lsattr hosts
----ia--------e------- hosts
root@VM-16-14-debian:/etc# chattr -ia hosts
root@VM-16-14-debian:/etc# lsattr hosts
--------------e------- hosts
root@VM-16-14-debian:/etc# chmod u+w hosts
