Changes

# Add the following lines in your shell script <u>IMMEDIATELY AFTER</u> the read statement to prompt the user for a mark:<br><span style="font-family:courier;font-weight:bold;">while ! echo $mark | egrep "^[0-9]{1,}$" > /dev/null 2> /dev/null<br>do<br> &nbsp;&nbsp;&nbsp;read -p "Not a valid number. 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 ''':x''' followed by '''ENTER''').<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>

# 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>