sudo root免密码

新建了个hadoop用户，想让他sudo切换到root免密码
终端输入

nano  /etc/sudoers

ubuntu16.04是以下内容

#
# This file MUST be edited with the 'visudo' command as root.
#
# Please consider adding local content in /etc/sudoers.d/ instead of 
# directly modifying this file.
#
# See the man page for details on how to write a sudoers file.
#
Defaults        env_reset
Defaults        mail_badpass
Defaults        secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin"

# Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root    ALL=(ALL:ALL) ALL

# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL

# Allow members of group sudo to execute any command
%sudo   ALL=(ALL:ALL) ALL

# See sudoers(5) for more information on "#include" directives:

#includedir /etc/sudoers.d

它说不要直接改这个文件，要改就去改/etc/sudoers.d/的。

cd /etc/sudoers.d/
ls

看看这个目录有什么

root@ubuntu03:~# cd  /etc/sudoers.d/
root@ubuntu03:/etc/sudoers.d# ls
90-cloud-init-users  README

我这里看到有个90-cloud-init-users
nano 90-cloud-init-users打开看看
里面有个ubuntu用户已经是免密码的，在下面加上新增的hadoop用户就OK了。

# User rules for ubuntu
ubuntu ALL=(ALL) NOPASSWD:ALL
hadoop ALL=(ALL) NOPASSWD:ALL