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Copying source code in your home directory.

  You can run the following command to copy the entire hw4 directory into your
home directory:
    cp -r /home/kapil/.www/courses/cs3650/homework/hw4 ~/hw4

  Now change permissions on this directory so others can't look inside it:
    chmod -R 700 hw4

  Now you can safely add/edit files in hw4 directory.

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Submitting homework:

When you are done, do:
  make dist    [ This will create a gzipped tar file, such as hw4.tar.gz .]
Then submit it online:
  /home/kapil/.www/courses/cs3650/homework/submit-cs3650-hw4   hw4.tar.gz

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Makefile:
  This assignment introduces Makefile.  They are there to make your life
easier.  A Makefile is a list of "targets" with "dependencies" such as:
TARGET: DEPENDENT_FILE1 DEPENDENT_FILE2
<TAB> COMMAND1
<TAB> COMMAND2

Read Makefile for an example.  To use Makefile, pick a target (e.g. run,
and do:
  make run

Note that the command "make" looks for a default file, "Makefile",
in the current directory, and then executes the commands in "Makefile".

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Linux Productivity Tools:
  While I can't enforce this, I encourage all students to use this assignment
to start learning Linux productivity tools.  A little investment of time now
will help you do later homeworks faster, and it will also look good to any
coop employer using Linux/Android as one part of their toolchain.  Hence,
I include two small tutorials:

1.  EDITOR:  vitutor.vi :  To start,
	cp /course/cs3650/editors-unix/vitutor.vi ~/
	cd ~
	vi vitutor.vi
    # In about an hour, you will learn all the basic vi commands, and practice
    # them directly, as you read through vitutor.vi in 'vi' itself.
    # If you prefer, emacs is another fine editor for Linux.  I demonstrate 'vi'
    #   here, because it has a little more mindshare at this time.

2.  DEBUGGER:  gdb : Text-oriented, but includes many powerful debugging
      commands, including 'step', 'next', 'break' (breakpoints), 'continue'
      Many of you found breakpoints to be useful in debugging the second
      assembly assignment.  They're also very powerful for C and other languages.

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DEBUGGING:

For each system call, you can automatically print errors.  We illustrate
with the call to "close()":
 if (-1 == open(argv[1])) {
     perror("open");
     exit(1);
 }

You can also use gdb (debugger, line-oriented version of Eclipse, but
	but much smaller and simpler).  If you use gdb on an executable
        make sure first that the executable was compiled using "gcc -g -O0".
        "-g" means to include extra debugging information in symbol table.
        "-O0" means to do 0 optimizations, so that the assembly code
	corresponds to the high level C code.
gdb --args myshell
(gdb) break main
(gdb) run
(gdb) # list at line 30
(gdb) list 30
(gdb) print argc
(gdb) print argv[0]
(gdb) # print type of variable
(gdb) ptype argv(0)
(gdb) ptype argv
(gdb) # display C stack
(gdb) where
(gdb) # next line, step over, not into, functions
(gdb) next
(gdb) # set a breakpoint at a function, and continue until there
(gdb) break getargs
(gdb) continue
(gdb) # if it's a function, step into it ('next' would go over it to next line.)
(gdb) step
(gdb) quit

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