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Tutorial12: Shell Scripting - Part 2

203 bytes added, 24 March
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# Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':x''' followed by '''ENTER''').<br><br>
# Run your shell script by issuing:<br><span style="color:blue;font-weight:bold;font-family:courier;">./if-5.bash</span><br><br>
# When prompted, enter a '''letter''' <u>instead</u> of a ''number''. What happens?<br>Does the shell script allow you to enter an invalid grade like '''200''' or '''-6'''?<br><br>Let's add an '''additional error-checking loop''' to force the user to enter a number between '''0''' and '''100'''.<br><br>Compound operators like '''&&''' and '''||''' can be used with the test command. Let's use the '''||''' compound criteria to to NOT accept numbers '''outside''' of the range '''0''' to '''100'''.<br><br>
# Use a text editor like vi or nano to edit the text file called '''~/if-5.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi ~/if-5.bash</span>)<br><br>
# Add the following lines in your shell script <u>IMMEDIATELY AFTER</u> the PREVIOUSLY ADDED<br>error-checking '''while''' loop statement to '''force''' the user to enter a valid number (between 1 and 100):<br><span style="font-family:courier;font-weight:bold;">while [ $mark -lt 0 ] || [ $mark -gt 100 ]<br>do<br> &nbsp;&nbsp;&nbsp;read -p "Invalid number range. Enter a mark (0-100): " mark<br>done</span><br><br>

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