Solutions to Lab 9
------------------
                                                                                
0. PATH=$PATH:<your home directory/lab9>

1. PS1=<your choice here>

2. Here's a script:
#!/bin/bash
echo "Please enter the first number:"
read first
echo "Please enter the second number:"
read second
echo "The product is" `expr $first \* $second`
                                                                                
3. Here's a script:
#!/bin/bash
files=`ls $1`
tot=0
for i in $files
do
   siz=`ls -l $i | awk '{print $5}'`
   tot=`expr $tot + $siz`
done
echo $tot
                                                                                
4. Here's a one-line script so full of itself.

#!/usr/bin/gawk {print;}

Another answer is:

#!/bin/cat