Execute 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

After this you can type sudo <whatever you want> in a Terminal window without being prompted for the password.

This only applies, to using the sudo command in the terminal. You'll still be prompted for your password if you (for example) try to install a package from the software center

sudo -i is the way to go if you don't want to be typing a password every 10 mins while doing modifications in your system (or other systems), and you don't want to modify any system files.

It will switch you to root using your sudo user password, when you close the console or type exit you are back to your normal user.

The preferred way to grant individual (or group) permissions would be to add files under /etc/sudoers.d

This separates local changes from the default policy and saves time in case the distribution sudoers file changes.

To make the currently logged in user a a sudoer and make sudo not prompt them for a password, use

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

this will create a file called /etc/sudoers.d/$USER (where $USER is the username of the user that you were logged in as when you ran that command), making it clear which users are granted permission.

If you want to do that for a different user, just replace both instances of $USER with some other username in the above command.

echo "otheruser ALL=(ALL:ALL) NOPASSWD: ALL" | sudo tee /etc/sudoers.d/otheruser

Similarly, one file can be used to manage multiple directives:

echo "username ALL=(ALL:ALL) NOPASSWD: ALL" | sudo tee -a /etc/sudoers.d/local

See /etc/sudoers.d/README and man sudoers for more information.

Root sudo timeouts are the easiest and safest way of doing this. I'll lay out all examples but be warned it is very risky any way you do this although this way is much safer:

sudo visudo

This opens an editor and points it to the sudoers file -- Ubuntu defaults to nano, other systems use Vi. You're now a super user editing one of the most important files on your system. No stress!

(Vi specific instructions noted with (vi!). Ignore these if you're using nano.)

Use the arrow keys to move to the end of the Defaults line.

(vi!) press the A (capital "a") key to move at the end of the current line and enter editing mode (append after the last character on the line).

Now type:

,timestamp_timeout=X

where X is the timeout expiration in minutes. If you specify 0 you will always be asked the password. If you specify a negative value, the timeout will never expire. E.g. Defaults env_reset,timestamp_timeout=5.

(vi!) hit Escape to return to command mode. Now, if you're happy with your editing, type in :w Enter to write the file and :q Enter to exit vi. If you made a mistake, perhaps the easiest way is to redo from start, to exit without saving (hit Escape to enter the command mode) and then type :q! Enter.

Hit Ctrl+X, then Y, then Enter to save your file and exit nano.

You might want to read the sudoers and vi manual pages for additional information.

man sudoers
man vi

Reset timeout value using:

sudo -k

These instructions are to remove the prompt for a password when using the sudo command. The sudo command will still need to be used for root access though.

Edit the sudoers file

Open a Terminal window. Type in sudo visudo. Add the following line to the END of the file (if not at the end it can be nullified by later entries):

<username> ALL=NOPASSWD: ALL

Replace <username> with your username (without the <>). This is assuming that Ubuntu has created a group with the same name as your user name, which is typical. You can alternately use the group users or any other such group you are in. Just make sure you are in that group. This can be checked by going to System -> Administration -> Users and Groups.

Example:

michael ALL=NOPASSWD: ALL

Type in ^X (Ctrl+X) to exit. This should prompt for an option to save the file, type in Y to save.

Log out, and then log back in. This should now allow you to run the sudo command without being prompted for a password.

The root account

Enabling the root account

Enabling the root account is rarely necessary. Almost everything you need to do as administrator of an Ubuntu system can be done via sudo or gksudo. If you really need a persistent root login, the best alternative is to simulate a Root login shell using the following command:

sudo -i

However, if you must enable root logins, you can do it like this:

sudo passwd root

Re-disabling your root account

If for some reason you have enabled your root account and wish to disable it again, use the following command in the terminal:

sudo passwd -dl root

System-wide group sudo

root$ echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers

Log out, and then back in.

Reset sudo timeout

You can make sure sudo asks for password next time by running:

sudo -k

Of course what you want to do isn't recommended. After a while, though entering sudo becomes so automatic that its usefulness diminishes.

Another approach is to leave your sudoers file as is and, while doing something complicated to your umpteen hundred servers, enter sudo bash . That will give you a shell that will be authenticated as root until you exit it.

Nice one-liner to remove sudo prompts for the current user

sudo bash -c 'echo "$(logname) ALL=(ALL:ALL) NOPASSWD: ALL" | (EDITOR="tee -a" visudo)'

From Super User comes a good answer:

Use the -S switch which reads the password from STDIN:

echo <password> | sudo -S <command>

Replace <password> with your password.

This is a one line solution that also changes files permissions as stated in /etc/sudoers.d/README:

sudo sh -c 'echo "$(logname) ALL=(ALL:ALL) NOPASSWD: ALL" > /etc/sudoers.d/$(logname)' && sudo chmod 440 /etc/sudoers.d/$(logname)

One liner

sudo sed -i /etc/sudoers -re 's/^%sudo.*/%sudo ALL=(ALL:ALL) NOPASSWD: ALL/g'

• Expanding on @upteryx idea.

• This is how I've implemented the non-root, passwordless user in an ephemeral Docker Image for use in a CICD pipeline:

RUN \
    groupadd -g 999 foo && useradd -u 999 -g foo -G sudo -m -s /bin/bash foo && \
    sed -i /etc/sudoers -re 's/^%sudo.*/%sudo ALL=(ALL:ALL) NOPASSWD: ALL/g' && \
    sed -i /etc/sudoers -re 's/^root.*/root ALL=(ALL:ALL) NOPASSWD: ALL/g' && \
    sed -i /etc/sudoers -re 's/^#includedir.*/## **Removed the include directive** ##"/g' && \
    echo "foo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers && \
    echo "Customized the sudoers file for passwordless access to the foo user!" && \
    echo "foo user:";  su - foo -c id