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Let'S talk about sudo, because sudo
is a more sophisticated way to grant

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users privileges to run specific tasks
or all tasks with elevated permissions.

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The default user is an administrator user,
and that user has sudo privileges by default.

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This default user is the user that you
would normally create when you install your distribution

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on red hat. This user has sudo privileges
because it's a member of the group wheel.

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And when on red hat, you
create a root user with a

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password, then you should know
there is no default admin user.

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On Ubuntu, it's easier. The root user never
has a password by default, so you get a

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default administrative user who is administrative user because
this user is a member of the group sudo.

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As a sudo enabled user, you can use sudo
command to run the command with escalated privileges, or

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you can use sudo I to open a root
shell. That's not really recommended, but sometimes it's convenient

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if you know beforehand that there are multiple
commands that you need to run with administrative privileges.

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Let me
show you.

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So, to start with, I'm using LS l root. That's my
favorite sudo test. What do you think? Is this going to work?

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It doesn't, because I'm not using sudo
to use my sudo superpowers. I need to

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start this command using sudo. So sudo
LS l root that is actually working.

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So I'm entering the password that is the
password for my current user account, and that is

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enabling my sudo powers. Now, the funny fact
is that I won't have to enter my password

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for the next five minutes. So if I
would use sudo password wdlinda to set a password

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for user linda, then it's not prompting for
a password. Well, it's prompting for a password.

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But that's because I'm using the passwd command to
set the password I don't have to authenticate again.

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That's because when you use sudo, an authentication token
is generated after you have entered the password Based on

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that authentication token, you can continue using sudo without
re entering the password for the next five minutes.

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Now, let me also show you sudo I and sudo
I is opening a root shell. As you can see,

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I'm now root at linfen and the hash in my
prompt is also indicating that I'm in a root shell.

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Once you are done in your root shell, don't forget
to type exit to get back to your normal operational environment.

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There's a few more things that we need
to discuss. Let's get back to the slides.

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This is about
using the right shell.

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Let's say you want to use sudo echo
hello greater than great then var log messages.

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Now the thing is that that is not working because
the greater than greater than is interpreted by the current shell.

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That goes for all the shell metacharacters like
redirects, like pipes and more. If you want to

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use them in sudo command then this is
how you use sudo sh c and then between

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double quotes you have the entire command that
you want to run. Let me show you.

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So to start it sudo echo hello
great then great then var log messages

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is giving a permission denied and that's
surprising but that's because of interpretation of

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the current shell. So if we change
that to sudo sh c and we

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put the entire command between double
quotes then suddenly it does work.

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That is nice to remember. If ever
you use shell metacharacters in your sudo.