==========================
CST8129 Challenge Projects
==========================
-IAN! idallen@ncf.ca

Here are some "challenge" projects that I think the more advanced
students should be able to do without too much trouble.

These aren't worth any marks; but, they are worth experience points.
I think you can do these things with minimal coding (and maximum RTFM).

If you are working on any of these projects, let me know.  I'd like to
see how you solve them.

*)  Modify simpleshell.c and add a built-in "exit" command that
    calls the C exit() function to exit the program.  (Bonus: if there
    is a command line argument, convert the character string argument
    to an integer using strtol() and pass that integer as the first
    argument to the exit() function.)

*)  Modify simpleshell.c and add a built-in "cd" command that calls the
    Unix chdir() function with its one command line argument.  (Make sure
    there is *exactly* one argument!)  (Bonus: print an error message if
    the chdir() function fails.)

*)  Modify simpleshell.c and add a built-in "umask" command that calls the
    Unix umask() function.  If there are no arguments, print out the
    current value of the umask (in octal, with leading zeroes, just as
    bash would do it).  If there is exactly one argument after "umask",
    convert the string to an integer using strtol() (base: octal!) and
    pass the integer to the umask() function to set the new umask.

*)  Write a C program to read a file in DOS format and write it out in
    Unix format.  (Convert CR+LF into just LF.)  You could write it as a
    filter (read stdin; write stdout); or, you could accept a file name
    (e.g. "foo"), process "foo" into a temp file, rename the "foo"
    to "foo.bak" (using the Unix rename() function), and rename the
    temp file to be "foo".  Check all the error returns from all the
    functions used.  (Bonus: only convert CR+LF to LF; do not touch a
    CR if it isn't followed by a LF.)

*)  Modify simplepipe.c and remove the read() call and error checking
    from the child process, replacing it with an execlp() of the command
    "cat".  Now try an execlp() of "wc".  Now try "tr [a-z] [A-Z]"
    (that is the "tr" command with two arguments).   You can copy the
    execvp() code from simpleshell.c and modify it to use execlp()
    instead of execvp(); or, you can keep using execvp() if you prefer.
    Make sure you copy all the error checking too.

*)  Modify simplepipe.c and remove the write() call and error checking
    from the parent process, replacing it with an execlp() of the command
    "date".  Now try an execlp() of "who".  Now try "echo Good Morning"
    (that is the "echo" command with two arguments).  You can copy
    the execvp() code from simpleshell.c and modify it to use execlp()
    instead of execvp(); or, you can keep using execvp() if you prefer.
    Make sure you copy all the error checking too.