[[email protected] Desktop]# cd ~

[[email protected] ~]# visudo  （sudo許可權修改）

Visudo （按a，i，o進入編輯模式）

（：set nu編號，找到第99行左右） 

[[email protected] Desktop]# whereis cat 通過whereis 找到cat命令的路徑

Cat:/usr/bin/cat/usr/share/man/man1/cat.1.gz/usr/share/man/man1p/cat.1p.gz

[[email protected] Desktop]# whereis ls尋找命令路徑

ls:/usr/bin/ls/usr/share/man/man1/ls.1.gz/usr/share/man/man1p/ls.1p.gz

97 ## Allow root to run any commands anywhere

98 root    ALL=(ALL)       ALL(能執行所有的命令)

99 lisi李四使用者擁有ALL所有地點=(ALL)最高許可權訪問

/usr/bin/cat,/usr/bin/ls 使用ls及cat命令許可權(注意必須是全命令格式)

esc 進入命令模式, :wq! 強制儲存並推出.

 [[email protected] ~]# su – lisi 變更到使用者李四

 [[email protected] ~]$ cat /etc/shadow 檢視shadow的內容

cat: /etc/shadow: Permission denied 不讓檢視

[[email protected] ~]$ sudo cat /etc/shadow 由於設定過visudo 李四的cat

許可權，所以使用sudo cat /etc/shadow 命令，輸入密碼就可以查看了

 We trust you have received the usual lecture from the local System

Administrator. It usually boils down to these three things:

 #1) Respect the privacy of others.

  #2) Think before you type.

  #3) With great power comes great responsibility.

 [sudo] password for lisi: 輸入李四密碼

root:$6$LUHZo5fyQvu7wIIT$THPpSKpmp1ojH7gPmXdc1ZOiwuz3TMa1Zj8t7HT2VlFoGAo4di3O1aBiSXTs/e0aO9YnxV1n9NhpCmpegkBQs0:17847:0:99999:7::（sudo命令授權李四可以檢視、shadow文件的內容）:

bin:*:16141:0:99999:7:::

daemon:*:16141:0:99999:7:::

adm:*:16141:0:99999:7:::

lp:*:16141:0:99999:7:::

sync:*:16141:0:99999:7:::

shutdown:*:16141:0:99999:7:::

halt:*:16141:0:99999:7:::

mail:*:16141:0:99999:7:::

operator:*:16141:0:99999:7:::

games:*:16141:0:99999:7:::

ftp:*:16141:0:99999:7:::

nobody:*:16141:0:99999:7:::

dbus:!!:17847::::::

polkitd:!!:17847::::::

unbound:!!:17847::::::

colord:!!:17847::::::

usbmuxd:!!:17847::::::

avahi:!!:17847::::::

avahi-autoipd:!!:17847::::::

libstoragemgmt:!!:17847::::::

saslauth:!!:17847::::::

qemu:!!:17847::::::

rpc:!!:17847:0:99999:7:::