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Linux sudo revoke permissions

 sudo is quite a good tool in Linux world in which you can specify commands with full access without giving root permissions to everything on the system.

 However, sudo can also be used to have access or root permissions to everything on the system.

 Why use sudo, when it can access everything? Why not just use or switch to root?

 When entering or executing a command, sudo is a safe haven to make sure you know exactly what you are doing or it can provide you a second chance to abort the command. If the command being entered isn't the right one, before entering the password or pressing enter "Ctrl + C" can be used to abort the command and stop the execution.

When running on a root session, any commands executer after pressing enter. There's no way to cancel or abort the command. That's why sudo is a good practice to use, so any of change of mind before pressing enter can is still possible to cancel.

And running in a non-root session, if the command is executed accidentally that will harm or delete an important setting it will be denied by the system. If it requires a root permission, if the command was executed on a root permission, then the command will be executed and whatever consequences after running the command will immediately take effect on the system.

 Although, sudo can provide us a safe haven to make sure root commands are not executed right away, or a password is needed to make sure the command is run by an authorized person on the system that knows what he or she is doing.

After the password is entered on the system, on the current session "sudo" will have 15 minutes by default that it won't ask for a password and any commands preceded by sudo, it will be executed automatically.

So, if you need to make changes on the system and need 5 minutes or less and don't want to wait the 15 minutes expiry?

 Type: sudo -k

This will require a sudo password or revoke the sudo on the current session and the next time, sudo is invoke a password would be required.

sudo -k or sudo -K is a good command to remember especially on a shared VM.

To learn more about sudo, consul the man page.

Below is an excerpt from the sudo man page.

man sudo

-K, --remove-timestamp

                 Similar to the -k option, except that it removes the user's cached credentials entirely and may not be used in conjunction with a command or other option.  This option does not require a password.  Not all security policies support credential caching.

-k, --reset-timestamp

                 When used without a command, invalidates the user's cached credentials.  In other words, the next time sudo is run a password will be required.  This option does not require a password and was added to allow a user to revoke sudo permissions from a .logout file.

                 When used in conjunction with a command or an option that may require a password, this option will cause sudo to ignore the user's cached credentials.  As a result, sudo will prompt for a password (if one is required by the security policy) and will not update the user's cached credentials.


Cheers! Take care. Till next Time. Enjoy Sudo'ing. Explore Linux and enjoy the journey..

Stay safe! and Keep things up! 

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