=== Part 3: Using the Command Line for VM Backup & State Management===

{{Admon/tip|Bash Shell Scripting Tips:|<br>'''<u>Data Input</u>'''<br><ul><li>A shell script can obtain data from a number of methods: '''reading input files''', using '''arguments when issuing command''' (positional parameters), or '''prompting for data to store in a variable'''. The later method can be accomplished by using the '''read''' command.<br><br></li><li>Example:<br><br>''read -p "Enter your name: " userName''.<br><br></li></ul>'''<u>Mathematical Expressions</u>'''<br><ul><li>In the bash shell scripting, data is stored in variable as text, not other data types (ints, floats, chars, etc) like in compiled programs like C or Java. In order to have a shell script perform '''mathematical operations''', number or variable need to be surrounded by two sets of parenthesis '''((..))''' in order to convert a number stored as text to a binary number.<br><br></li><li>Examples<br><br>''var1&#61;5;var2&#61;10''<br>''echo "$var1 + $var2 &#61; $((var1+var2))"''<br><br>'''Note:''' shell does not perform floating point calculations (like '''5/10'''). Instead, other commands like '''awk''' or '''bc''' would be required for floating point calculations (decimals)<br><br></li></ul>}}

You will continue our use of the Bash Shell scripting by first creating a Bash Shell script that examining commands will allow the Linux sysadmin to select gather information about and manage their created VMs for backup to root's home directory. Afterwards you will download, view and run a couple Bash Shell scripts that use the virsh command to start and stop your virtual machinesVirtual Machines.