su切换用户与sudo提权

如果想针对所有用户以及登录与非登录shell设置统一的配置----》/etc/bashrc
[root@web01 ~]# vim /etc/bashrc
[root@web01 ~]# source /etc/bashrc # 当前环境让该文件生效
或者重启也可以生效

[root@allenzhu ~]# visudo -c  检查配置是否正确
/etc/sudoers: parsed OK

(2)vim /etc/sudoers

[root@test ~]# cat /etc/sudoers
## 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
主机别名

## Groups of machines. You may prefer to use hostnames (perhap 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地址代替，这时可以配置主机别名.

# Host_Alias FILESERVERS = fs1, fs2
# Host_Alias MAILSERVERS = smtp, smtp2

 User Aliases
用户别名

## 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/sbin/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

#环境变量的相关配置
# Defaults specification
#
# Disable "ssh hostname sudo <cmd>", because it will show the password in clear.
# You have to run "ssh -t hostname sudo <cmd>".
#
Defaults requiretty
Defaults env_reset
Defaults env_keep = "COLORS DISPLAY HOSTNAME HISTSIZE INPUTRC KDEDIR \
LS_COLORS MAIL PS1 PS2 QTDIR USERNAME \
LANG LC_ADDRESS LC_CTYPE LC_COLLATE LC_IDENTIFICATION \
LC_MEASUREMENT LC_MESSAGES LC_MONETARY LC_NAME LC_NUMERIC \
LC_PAPER LC_TELEPHONE LC_TIME LC_ALL LANGUAGE LINGUAS \
_XKB_CHARSET XAUTHORITY"

## 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.
# %sys ALL = NETWORKING, SOFTWARE, SERVICES, STORAGE, DELEGATING, PROCESSES, LOCATE, DRIVERS
 允许sys中户组中的用户使用NETWORKING等所有别名中配置的命令

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

## 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
# %users localhost=/sbin/shutdown -h now
 允许users用户组中的用户像root用户一样使用shutdown命令