Chapter 10

1. Nothing

You should use the variable name without the dollar sign to print it.

2. Solution: zero

Because you should print $1 instead of $2 where $1 is the first field.

3. The while loop should iterate with i value less than 4 not 3.
4. 1

Because the only user that has UID less than 1 is root (UID=0), so one line will be printed.