Thinks you should know about sudo command

Jephe Wu -

Envirnment: CentOS 6.4 64bit
Objective:  understanding sudo command and common usages.

<username1> <ALL hosts>=(username2) [NOPASSWD:] commands

Above syntax will grant username1 to run commands as username2 on all hosts

1. sudo -l after you ssh into server

sudo -l will list the possible commands you could run

2. sudo -i  to become root ( similiar to su - , using root user environment configuration including $HOME and $PATH)

Other similiar command such as sudo -s, sudo su and sudo bash.

3. sudo -k to clear password cache 

You can also configure password cache time (minutes) in /etc/sudoers, by default, it's cached for 5 minutes, change to 0 will always ask for


[root@server1 ~]# grep -i timestamp_timeout /etc/sudoers
Defaults timestamp_timeout=1

To totally disable password prompt, use  NOPASSWD: between (ALL) and right-most ALL

<username> ALL=(ALL) NOPASSWD: ALL

4. always use visudo to edit /etc/sudoers instead of vi /etc/sudoers
visudo check syntax error

So you can remember above sudo command parameters by LIK(e), e for edit which uses visudo.

Refer to