ICS54
                            =====
                        Assignment #2
                Due Tues. Jan 18 at 8am SHARP.

(2) 1. Explain what happens with
	  $ cat x y > y
       and with
	  $ cat x >> x
    Think before you rush off to try them.

(2) 2. Write a short shell script called "cx" that will execute the command
       "chmod +x" on every file given on its command  line.  What does it do?

(2) 3. Write a short shell script called "nf" to display the number of
       files in the current directory.

(4) 4. Write a shell script called "lss" that will list all the files in
       the current directory in decreasing order of the number of bytes in
       the file.  It does not need to take any arguments.  Eg.,

         $ lss
         -rwxrwxr--    1 admins   Administ      385 Nov 29  1996 lss
	  -rwxrwxr--    1 admins   Administ       42 Mar  9  1990 nf

(4) 5. Write a shell script called "whoson" to display a sorted list of
       undergrad students logged in on the current machine.  You should
       take a look at the command called "groups" to acquire some of
       the requisite information. eg.,
         $ whoson
         john jane jim frank laura

(2) 6. Write a shell script called "howmany" to display the number of
       undergrad students logged in on the current machine.  eg.,
         $ howmany
         5

(4) 7. Write a shell script called "valid" that determines if it's
       argument is a valid shell variable name, eg
         $ valid foobar
         yes
         $ valid 12foobar
         no

        (HINT: define a regular expression, and enlist the aid of "grep".)

(4) 8. Write a shell script called "prargs" that prints out a numbered
       list of its arguments in the following format:
         $ prargs a 'b c'
         0: "prargs"
         1: "a"
         2: "b c"

(4) marks for overall presentation, ie neatness counts!

Make the shell scripts as "bulletproof" as possible; they should never blow
up, and if used incorrectly should print an error or usage message.  Submit
each electronically (details to be given on Thursday). Additionally, submit
a printout of each, plus external documentation on how they work.  ASCII is
acceptable, or any other form of word processor.