SHELL

sudo no password

# Run the following command
sudo visudo

# Add the following to the bottom of the file and substitute 'username'
# for your own linux username
username     ALL=(ALL) NOPASSWD:ALL

sudo without password linux

echo "$USER ALL=(ALL) NOPASSWD:ALL" | sudo tee -a /etc/sudoers

sudo without password

You can configure sudo to never ask for your password.

Open a Terminal window and type:

sudo visudo
In the bottom of the file, add the following line:

$USER ALL=(ALL) NOPASSWD: ALL
Where $USER is your username on your system. Save and close the sudoers file (if you haven't changed your default terminal editor (you'll know if you have), press Ctl + x to exit nano and it'll prompt you to save).

As of Ubuntu 19.04, the file should now look something like

#
# This file MUST be edited with the 'visudo' command as root.
#
# Please consider adding local content in /etc/sudoers.d/ instead of
# directly modifying this file.
#
# See the man page for details on how to write a sudoers file.
#
Defaults    env_reset
Defaults    mail_badpass
Defaults    secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin"

# Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root    ALL=(ALL:ALL) ALL

# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL

# Allow members of group sudo to execute any command
%sudo   ALL=(ALL:ALL) ALL

# See sudoers(5) for more information on "#include" directives:

#includedir /etc/sudoers.d

YOUR_USERNAME_HERE ALL=(ALL) NOPASSWD: ALL

sudoer sudo no password NOPASSWORD

#RECOMMENDED
cp /etc/sudoers /root/sudoers.bak
visudo
leonard ALL = NOPASSWD: /bin/systemctl restart httpd.service, /bin/kill

#NOT RECOMMENDED
cp /etc/sudoers /root/sudoers.bak
visudo
leonard ALL=(ALL) NOPASSWD:ALL

#TEST
sudo ls -ls /root

sudo without password

# Run the following command
sudo visudo

# Add the following to the bottom of the file and substitute 'username'
# for your own linux username
username     ALL=(ALL) NOPASSWD:ALL