TL;DR
假设用户名为user密码是hello
echo hello | sudo -S sh -c "echo 'user ALL=(ALL) NOPASSWD: ALL' >> /etc/sudoers.d/user-nopasswd"
sudo chmod 440 /etc/sudoers.d/user-nopasswd
设想
每次输入sudo密码很繁琐，希望sudo免密码执行
对应很多服务器，写shell脚本批量修改
思考
网上多数方法通过向/etc/sudoers文件末尾插入user ALL=NOPASSWD:ALL实现免密
文件头部如下
#
# 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.
#
官方建议我们不要直接修改本文件而是使用sudoer.d中的本地设置
#
# As of Debian version 1.7.2p1-1, the default /etc/sudoers file created on
# installation of the package now includes the directive:
#
# #includedir /etc/sudoers.d
#
# This will cause sudo to read and parse any files in the /etc/sudoers.d
# directory that do not end in '~' or contain a '.' character.
#
# Note that there must be at least one file in the sudoers.d directory (this
# one will do), and all files in this directory should be mode 0440.
#
# Note also, that because sudoers contents can vary widely, no attempt is
# made to add this directive to existing sudoers files on upgrade. Feel free
# to add the above directive to the end of your /etc/sudoers file to enable
# this functionality for existing installations if you wish!
#
# Finally, please note that using the visudo command is the recommended way
# to update sudoers content, since it protects against many failure modes.
# See the man page for visudo for more information.
#
系统会自动加载sudoers.d文件夹下名称不含~.的文件
实现
假设用户名为user密码是hello
推荐方法：添加本地sudoers.d
echo hello | sudo -S sh -c "echo 'user ALL=(ALL) NOPASSWD: ALL' >> /etc/sudoers.d/user-nopasswd"
sudo chmod 440 /etc/sudoers.d/user-nopasswd
不推荐方法：直接修改sudoers
echo hello | sudo -S sed -i '$a user ALL=(ALL) NOPASSWD: ALL' /etc/sudoers