In Unix systems like Linux, some commands are considered dangerous and only the
root user can run them. Normally, you don't login as
root. So when you want to run dangerous commands, you must first become
root. Then you run your dangerous stuff, and go back to your own user.
This switching between users is tedious and many people don't like it. So the
sudo command was created to automate the process.
sudo some_command is equivalent to:
1. Log out
2. Log in as root
3. Run some_command
4. Log out
5. Log in as your normal user
But it is nicer because it inherits most of your user environment. For example,
sudo ls ~ is smart enough to print the contents of your actual home directory, instead of the root's home directory. This is because logging in as
root would set environment variables like
root's home (
sudo doesn't use the normal interactive login and does not change your
$HOME from the value corresponding to your normal user. There are many other small details like this that
sudo avoids for you.