An old bicycle lock has six keys, each taking one of trhree possible positions. How many combinations to test in a brute force attack.

How much is a password improved by changing the rules from 8 upper and lower case alphabetic characters only, to 12 upper and lower case characters, and digits.

A user wants to create a text file in hishome directory. He wants to read and write. Group members must only read. Others shoul have no permissions. Show how to achieve this in at least two different ways.

A user creates a directory with the profile 700. In this directory he creates files with 777 permissions. May others access the files? Why/why not?

You want all you files to have 437 permissions. How di you do that? How do you make sure that this configuration lasts?

Normally a user may change his own password on a Linux/UNIX system. Some systems decide that this is too risky, and they make this impossible. How?

What does tail -f /var/log/messages do? How do you and it? Who may do it?

In your home directory you have a directory dir1. You want to move all it's content to another directory dir2. Show the command given that your current working directory is your home directory. Show the command given that dir1 is the current working directory.

A file abc& must be deleted? How?

You need a long listing af files whose names start with "prog" and end with ".c". How?

You have a directory with, among others, the files got|cha og M*A*S*H". Show me a command that will disply the two files one screen at a time.

What does the following command do? rm *[a-zA-Z]??[1,5,8].[^p]*

You have two files, program1.c and program2.c. What is the difference between them?

Pring program1.c with the header "STAR TREK - main" on the printer sh-epson1. Show me the command?