$(10$ pts$)$ Write a simple shell script to move $($rename$)$ all $*.$PDF files under the current directory $($if any$)$ to $*.$pdf$,$ e$.$g$.,$

move test.PDF to test.pdf

move hello.PDF$.$PDF to hello.PDF$.$pdf

move $.$hello.PDF$.$PDF to $.$hello.PDF$.$pdf

and report each action, otherwise just report there are no $*.$PDF files.

This$\_$section helps the problem.

$(20$ pts$)$ Write a simple single thread CSC$4420$ shell $,$ i$.$e$.,$ no concurrent commands, to support at least the following built$-$in commands:

prompt can set to any string you input, in addition to the current history event number, i$.$e$,\%$ h as in csh;

url : list the course web site

hour : list class times

room : list classroom location

desp : list the description of this course

text : list the textbook

ref : list the reference books

prof : list the professor's name

pol : professor's office location

poh : professor's office hours

pma : professor's email address

ta : list the TA's name

tol : TA's office location

toh : TA's office hours

@ tma : TA's email address

history : list history of events up to the number you set

@ help : list all the available commands

@ exit or quit : exit CSC$4420$ shell