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Sudoers File Explained

You are probably wondering how the sudoers file works. Here’s a simple explanation.

Command

username host=(user:group) tag:commands

Explanation

    • username – the specified user allowed to run commands.
    • host – the specified host the command is allowed to run.
    • user – specifies which users can use the command.
    • group – specifies which groups can run the command.
    • tag – the option allowed. NOPASSWD
    • command – the command allowed to run.

Examples

root    ALL=(ALL) ALL
username ALL=(ALL) ALL
john test=(ALL) NOPASSWD: /bin/useradd
jane ALL=(sales) NOPASSWD: /bin/sh
%sudo ALL=(ALL) ALL
%adgroup ALL=(ALL) ALL

Wheel Group

Here’s an alternate way to give Linux users sudo access by adding them to the wheel group. Most Linux systems come with the wheel group already predefined. By adding users to the wheel group, they now have the ability to sudo and run root commands. The wheel group is in the sudoers file for Redhat, Centos, Debian and Ubuntu.

usermod -aG wheel username

Sudo With No Password

If you’re the only user on your system, you don’t need to be prompted every time you run the sudo command.

Add yourself to the sudoers file.

# create a new file
sudo visudo -f /etc/sudoers.d/users

Add this line.

# add your username
username ALL=(ALL) NOPASSWD:ALL

Exit and try again.

# exit out and login again
exit
# try to sudo again
sudo -i
# there's no password prompt for sudo this time