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2.5. Exercises

Most of what we learn is by making mistakes and by seeing how things can go wrong. These exercises are made to get you to read some error messages. The order in which you do these exercises is important.

Don't forget to use the Bash features on the command line: try to do the exercises typing as few characters as possible!

2.5.1. Connecting and disconnecting

  • Determine whether you are working in text or in graphical mode.

    I am working in text/graphical mode. (cross out what's not applicable)

  • Log in with the user name and password you made for yourself during the installation.

  • Log out.

  • Log in again, using a non-existent user name

    -> What happens?

2.5.2. Passwords

Log in again with your user name and password.

  • Change your password into P6p3.aa! and hit the Enter key.

    -> What happens?

  • Try again, this time enter a password that is ridiculously easy, like 123 or aaa.

    -> What happens?

  • Try again, this time don't enter a password but just hit the Enter key.

    -> What happens?

  • Try the command psswd instead of passwd

    -> What happens?

WarningNew password

Unless you change your password back again to what it was before this exercise, it will be "P6p3.aa!". Change your password after this exercise!

Note that some systems might not allow to recycle passwords, i.e. restore the original one within a certain amount of time or a certain amount of password changes, or both.

2.5.3. Directories

These are some exercises to help you get the feel.

  • Enter the command cd blah

    -> What happens?

  • Enter the command cd ..

    Mind the space between "cd" and ".."! Use the pwd command.

    -> What happens?

  • List the directory contents with the ls command.

    -> What do you see?

    -> What do you think these are?

    -> Check using the pwd command.

  • Enter the cd command.

    -> What happens?

  • Repeat step 2 two times.

    -> What happens?

  • Display the content of this directory.

  • Try the command cd root

    -> What happens?

    -> To which directories do you have access?

  • Repeat step 4.

    Do you know another possibility to get where you are now?

2.5.4. Files

  • Change directory to / and then to etc. Type ls; if the output is longer than your screen, make the window longer, or try Shift+PageUp and Shift+PageDown.

    The file inittab contains the answer to the first question in this list. Try the file command on it.

    -> The file type of my inittab is .....

  • Use the command cat inittab and read the file.

    -> What is the default mode of your computer?

  • Return to your home directory using the cd command.

  • Enter the command file .

    -> Does this help to find the meaning of "."?

  • Can you look at "." using the cat command?

  • Display help for the cat program, using the --help option. Use the option for numbering of output lines to count how many users are listed in the file /etc/passwd.

2.5.5. Getting help

  • Read man intro

  • Read man ls

  • Read info passwd

  • Enter the apropos pwd command.

  • Try man or info on cd.

    -> How would you find out more about cd?

  • Read ls --help and try it out.