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→INVESTIGATION 2: ADDITIONAL LOOPING STATEMENTS
# When prompted, enter a letter instead 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>
# Use a text editor like vi or nano to edit the text file called '''for-5.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi for-5.bash</span>)<br><br>
# Add the following lines in your shell script <u>AFTER</u> the PREVIOUSLY ADDED error-checking code block to force the user to enter a valid number:<br><span style="color:blue;font-family:courier;font-weight:bold;"><br>while [ $mark -lt 0 ] || [ $mark -gt 100 ]<br>do<br> read -p "Invalid number range. Enter a mark (0-100): " mark<br>done</span><br><br>
# Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').<br><br>
# Run your shell script by issuing:<br><span style="color:blue;font-weight:bold;font-family:courier;">./for-5.bash</span><br><br>
# Change line 6 to the following:<br><span style="color:blue;font-family:courier;font-weight:bold;">((value=value+1))</span><br><br>
# Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').<br><br>
# Add execute permissions for the owner of this script and run this script.<br>What do you notice? <br><br>
:In the next investigation, you will learn to create and test-out the '''~/.bashrc''' start-up file to customize your Bash shell.
