'''Control Flow Statements''' are used to make your shell scripts<br>more '''flexible''' and can '''adapt''' to changing situations.<br><br>In order to use control flow statements, you need to test a condition to get a TRUE or FALSE value. This can be done two ways:<ul><li>Run a command to get the exit status (<span style="font-family:courier;font-weight:bold;">$?</span>)</li><li>Use the '''test''' command</li></ul><br><br>Refer to the diagrams on the right to see how to use the test command.<br><br>

The special parameter '''$?''' Is used to determine the '''exit status''' of the previously issued Linux command.The exit status will either display a '''zero''' (representing TRUE) or a '''non-zero''' number (representing FALSE). The test command can be used with control flow statements to control the sequence of a shell script. You CANNOT use the '''<span style="font-family:courier;font-weight:bold;"></span>''' or '''<''' span style="font-family:courier;font-weight:bold;"></span> symbols when using the test command since these are redirection symbols. Instead, you need to use options when performing numerical comparisons.