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INVESTIGATION 4: CONTROL FLOW STATEMENTS
# Issue a Linux command to display the value of '''$?'''<br><br>'''NOTE:''' You will notice that something is '''wrong'''.<br>The exit status '''$?''' shows a zero (TRUE) value, but the number 5 is definitely NOT greater than 10.<br>The problem is that the symbols '''&lt;''' and '''&gt;''' are interpreted as REDIRECTION symbols!<br><br>
# To prove this, issue the following Linux command :<br><span style="color:blue;font-weight:bold;font-family:courier;">ls -l 10</span><br><br>You should notice a file called "'''10'''". The incorrectly issued '''test''' command '''used redirection'''<br>to create an '''empty''' file and assigning the exit status variable a ''TRUE'' value!<br><br>To prevent problems when issuing the '''test''' command when comparing numbers,<br>you can use the following options:<br>'''-lt''' (&lt;), '''-le''' (&lt;&#61;), '''-gt''' (&gt;), '''-ge''' (&gt;&#61;;), '''-eq''' (&#61;), '''-ne''' (!&#61;)<br><br>
# Issue the correct Linux command to '''properly ''' test both values:<br><span style="color:blue;font-weight:bold;font-family:courier;">test $number1 -gt $number2</span><br><br>
# Issue a Linux command to display the value of '''$?'''.<br><br>You should notice that the exit status value is now ''FALSE'' which is the correct result.<br><br>
# The '''test''' command can be substituted by '''square brackets''' '''&#91; &#93;''' which contains the '''test''' condition<br>within the square brackets. You need to have spaces between the brackets and the test condition;<br>otherwise, you will get a test error.<br><br>
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