Ubuntu 20.04: sudo without password

You can edit /etc/sudoers with visudo interactively. This article will edit /etc/sudoers with sed non-interactively. sudo needs password yet.

$ sudo sed -i /etc/sudoers -e 's/^%sudo.*/%sudo ALL=(ALL:ALL) NOPASSWD:ALL/g'
[sudo] password for hiroom2:

The /etc/sudoers is the following after adding NOPASSWD. sudo does not need password.

#
# 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) NOPASSWD:ALL

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

#includedir /etc/sudoers.d