Way to run sudo without running another unneccessary command

sudo

I wanted to run two sudo commands, piping the output from one to the other. However, when I haven't entered my password for sudo recently, it prompts me for the password. The pipes and two sudos seem to screw it up, so I can't correctly enter my password.

My solution to this is to run "sudo ls" or something else that prompts me for my password, so that the piped commands will work without asking me to enter it. This got me wondering if there was a "correct" way to run sudo such that you're not also running some other pointless command. The manpage for sudo doesn't seem to say anything about this.

Best Answer

What you are looking for is sudo -v. From the man page:

-v, --validate
          Update the user's cached credentials, authenticating the user
          if necessary.

(And the counterpart to explicitly remove the credentials: sudo -k)

Related Solutions

The correct way to abort an operation from the sudo password prompt

What I usually do is Ctrl + Z to suspend the task, then kill %1 or even kill -9 %1 to stop:

> sudo ls
[sudo] password for user:

Ctrl + Z

[1]  +   512 Suspended                     sudo ls
> kill %1
[1]  + Suspended (tty output)        sudo ls
> kill -9 %1
[1]    Killed                        sudo ls

(In case you have more background tasks in your shell: The number you need to give after the percent sign is the one in brackets []).

Sudo – Prevent Prompting for Password When Running Non-Permitted Command

From a quick read of sudo(8)

   -n          The -n (non-interactive) option prevents sudo from
               prompting the user for a password.  If a password is
               required for the command to run, sudo will display an error
               message and exit.

And for the doubters:

# grep jdoe /etc/sudoers
jdoe    ALL=(ALL) NOPASSWD: /bin/echo
#

Tested thusly:

% sudo echo allowed
allowed
% sudo -n ed             
sudo: a password is required
% sudo ed               

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

Password:

So an alias for sudo for these folks would likely do the trick, to prevent the password prompt. Now why this requires custom compiling sudo, I don't know, I just read the manual.

Best Answer

Related Solutions

The correct way to abort an operation from the sudo password prompt

Sudo – Prevent Prompting for Password When Running Non-Permitted Command

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