WARNING:

• In this exercise /etc/passwd is used, as it exists in every UNIX system.
  However it is not advised to use “vi” for user management!

1. Copy the file /etc/passwd to your HOME-directory.
   Name your copy mypasswd
   Hint: your HOME-directory is the base directory for you as a user.

HINTS:

• After you've inserted text, immediately return to Command Mode
• Use the vi-option :set showmode

1. Above the first line of this new file, add the line: This is just a test file!
   Hint: O (capital o)
2. Add a new user to your test file.
   Hint: yyp
3. See to it that the last line becomes the last line but one.
   Hint: ddp
4. For the last 5 user accounts add the comment: UNIX user
   Hint: The comment field is the 5th field in the passwd file.
   Hint: Use the vi repeat command to make things painless.
5. Make each line start with one TAB.
   Hint: Regular Expression characters ^ $
   Hint: :1,$s/ / /
6. Try to undo your last change.
   Hint: u
7. Use vi to copy all administrative users to a file called passwd.adm
   Hint: Administrative users are users like “root” and “lp”.
   This example shows how to copy lines to another file:

   "a5yy
   "b3yy
   ..
   ..
   :e passwd.adm
   "ap
   "bp

8. Quit vi.
   Check if you have a file named .exrc in your HOME-directory. Make a backup copy of your existing .exrc
   Create the file $HOME/.exrc containing the following two lines:

   :set showmode
   :set list

9. Use vi to reopen your test file and check which vi-options are available.
   Hint: :set all
10. In your test file, pick one of the user accounts and use <space> to add a blank at the end of the login shell field.
    Is this blank visible?
    Which vi-option will make it visible?
    What do you think? Would it stll be possible to login with a blank after the shell in the real /etc/passwd?
    Remember this option! It's an invaluable option in debugging a non functioning config file!

Copyright (C) 2011 Integrated Services; Tux4u.nl
Author: Ing.J.M.Waldorp
vi-exercise1 20030514, 20110417