Unix Assignment

1. What is significant about the recursive nature of functions?

2. Review the function below and answer the questions below. Function mycp when called copies the file named in the first argument to the file named by the second argument.

function mycp () {

case $# in

0)

exec 3<&0 4<&1

;;

1)

exec 3< $1 4<&1

;;

2)

exec 3< $1 4> $2

;;

*)

echo "Usage: mycp [source [dest]]"

return 1

;;

esac

cat <&3 >&4

exec 3<&- 4<&-

}

What happens if you supply one argument?

What happens if you supply no arguments?

Explain what is happening in line 18.

Explain what is happening in line 20.

3. Write a script named ifthen that prompts the user with >> and reads a string of text from the user. If the user enters a nonnull string, the script displays You entered: followed by the string; otherwise it displays Where is your input?. Use an if...then...else control structure to implement the two-way branch in the script. Use a test to determine if the user enters a null string. What do you have to do to avoid getting an error message when you prompt with >>?

Deliverables:

1. Submit your results for both null and nonnull test cases in your homework doc.

2. Submit your answer to the question regarding >> in your homework doc also.