[hadoop@localhost ~]$ visudo
visudo：/etc/sudoers：权限不够
visudo：/etc/sudoers：权限不够使用visudo命令打开sudo配置文件

## Sudoers allows particular users to run various commands as
## the root user, without needing the root password.
## 该文件允许特定用户像root用户一样使用各种各样的命令，而不需要root用户的密码
##
## Examples are provided at the bottom of the file for collections
## of related commands, which can then be delegated out to particular
## users or groups.
## 在文件的底部提供了很多相关命令的示例以供选择，这些示例都可以被特定用户或
## 用户组所使用 
##
## This file must be edited with the 'visudo' command.
## 该文件必须使用"visudo"命令编辑

## Host Aliases
## Groups of machines. You may prefer to use hostnames (perhaps using 
## wildcards for entire domains) or IP addresses instead.
## 对于一组服务器，你可能会更喜欢使用主机名（可能是全域名的通配符）
## 、或IP地址，这时可以配置主机别名
# Host_Alias   FILESERVERS = fs1, fs2
# Host_Alias   MAILSERVERS = smtp, smtp2

## User Aliases
## These aren't often necessary, as you can use regular groups
## (ie, from files, LDAP, NIS, etc) in this file - just use %groupname 
## rather than USERALIAS
## 这并不很常用，因为你可以通过使用组来代替一组用户的别名
# User_Alias ADMINS = jsmith, mikem

## Command Aliases
## These are groups of related commands...
## 指定一系列相互关联的命令（当然可以是一个）的别名，通过赋予该别名sudo权限，
## 可以通过sudo调用所有别名包含的命令，下面是一些示例

## Networking 网络操作相关命令别名
# Cmnd_Alias NETWORKING = /sbin/route, /sbin/ifconfig, /bin/ping, /sbin/dhclient
, /usr/bin/net, /sbin/iptables, /usr/bin/rfcomm, /usr/bin/wvdial, /sbin/iwconfig
, /sbin/mii-tool

## Installation and management of software 软件安装管理相关命令别名
# Cmnd_Alias SOFTWARE = /bin/rpm, /usr/bin/up2date, /usr/bin/yum

## Services 服务相关命令别名
# Cmnd_Alias SERVICES = /sbin/service, /sbin/chkconfig

## Updating the locate database 本地数据库升级命令别名
# Cmnd_Alias LOCATE = /usr/bin/updatedb

## Storage 磁盘操作相关命令别名
# Cmnd_Alias STORAGE = /sbin/fdisk, /sbin/sfdisk, /sbin/parted, /sbin/partprobe
, /bin/mount, /bin/umount

## Delegating permissions 代理权限相关命令别名
# Cmnd_Alias DELEGATING = /usr/sbin/visudo, /bin/chown, /bin/chmod, /bin/chgrp

## Processes 进程相关命令别名
# Cmnd_Alias PROCESSES = /bin/nice, /bin/kill, /usr/bin/kill, /usr/bin/killall

## Drivers 驱动命令别名
# Cmnd_Alias DRIVERS = /sbin/modprobe

# Defaults specification

#
# Disable "ssh hostname sudo <cmd>", because it will show the password in clear. 
#     You have to run "ssh -t hostname sudo <cmd>".
# 一些环境变量的相关配置，具体情况可见man soduers
Defaults  requiretty

Defaults  env_reset
Defaults  env_keep = "COLORS DISPLAY HOSTNAME HISTSIZE INPUTRC KDEDIR LS_COLORS"
Defaults  env_keep += "MAIL PS1 PS2 QTDIR USERNAME LANG LC_ADDRESS LC_CTYPE"
Defaults  env_keep += "LC_COLLATE LC_IDENTIFICATION LC_MEASUREMENT LC_MESSAGES"
Defaults  env_keep += "LC_MONETARY LC_NAME LC_NUMERIC LC_PAPER LC_TELEPHONE"
Defaults  env_keep += "LC_TIME LC_ALL LANGUAGE LINGUAS _XKB_CHARSET XAUTHORITY"

Defaults  secure_path = /sbin:/bin:/usr/sbin:/usr/bin

## Next comes the main part: which users can run what software on 
## which machines (the sudoers file can be shared between multiple
## systems).
## 下面是规则配置：什么用户在哪台服务器上可以执行哪些命令（sudoers文件可以在多个系统上共享）
## Syntax(语法):
##
## user MACHINE=COMMANDS 用户 登录的主机=（可以变换的身份） 可以执行的命令
##
## The COMMANDS section may have other options added to it.
## 命令部分可以附带一些其它的选项
##
## Allow root to run any commands anywhere 
## 允许root用户执行任意路径下的任意命令
root ALL=(ALL) ALL

## Allows members of the 'sys' group to run networking, software, 
## service management apps and more.
## 允许sys中户组中的用户使用NETWORKING等所有别名中配置的命令
# %sys ALL = NETWORKING, SOFTWARE, SERVICES, STORAGE, DELEGATING, PROCESSES, LOCATE
, DRIVERS

## Allows people in group wheel to run all commands
## 允许wheel用户组中的用户执行所有命令
%wheel ALL=(ALL) ALL

## Same thing without a password
## 允许wheel用户组中的用户在不输入该用户的密码的情况下使用所有命令
# %wheel ALL=(ALL) NOPASSWD: ALL

## Allows members of the users group to mount and unmount the 
## cdrom as root
## 允许users用户组中的用户像root用户一样使用mount、unmount、chrom命令
# %users ALL=/sbin/mount /mnt/cdrom, /sbin/umount /mnt/cdrom

## Allows members of the users group to shutdown this system
## 允许users用户组中的用户关闭localhost这台服务器
# %users localhost=/sbin/shutdown -h now

## Read drop-in files from /etc/sudoers.d (the # here does not mean a comment)
## 读取放置在/etc/sudoers.d/文件夹中的文件（此处的#不意味着这是一个声明）
#includedir /etc/sudoers.d