However, rm tries to be helpful, figuring that if you didn't want to
change the file (and thus remove write permission), you don't want to
delete it either, so it asks you.

What was that 0444 business in the question from rm? The permissions mode
is a twelve-digit binary number, like this: 000100100100. 0444 is this
binary number represented as an octal (base 8) number, which is the
conventional way to write a mode. So you can type chmod 444 myfile instead
of chmod ugo=r myfile.

Files Present and Their Locations

Now that you can navigate the directory tree, let's take a guided tour of
the files and directories you created when you installed Debian. If you're
curious, cd to each directory and type ls to see its contents. If the
listing doesn't fit on the screen, try ls | less, where | is the ``pipe''
character, generally found on the same key with backslash.

/
As already mentioned, this is the root directory, which contains
every other directory.

/root
But don't get /confused with /root! /root is the home directory of
the root user, or superuser. It's a directory called /root, but it
isn't the root directory /.

/home
This is where all normal users - that is, all users except root -
have their home directories. Each home directory is named after