[K12OSN] cron job how to

[Michael C Wescott]

On Thu, 2005-09-08 at 22:40 -0500, Liam Marshall wrote:
> I have a "homework folder" for each computer class where the owner is 
> the teacher of the class, the group is the group associated with that 
> class.  owner has read write execute, group has write and execute.  So 
> effectively, they can drag/drop off their assignments into this folder, 
> and after they close the window, can't access their own file, 
> effectively "handing in" their assignment.
> 
> I was quite pleased with myself until I went into one of my own class 
> homework folders.  I can see all the files( this is good) but cannot 
> open any!

This kind of setup isn't as nice as you might like. Consider the
scenario where two students each call their file "homework3.doc". The
student that submits last will either overwrite the first student's file
or will not be allowed to submit his work for reasons not readily
apparent to a student (i.e. "permission denied"). A malicious student
could still, knowing or guessing the file name, delete another's file as
well.

Consider, instead, something like this: each teacher has a directory for
each class and a subdirectory therein for each student. The student's
(sub)directory would be owned by the student. Submission would be done
by dropping the file(s) into the correct directory which could very well
be a symlink in the student's home directory. A simple script could then
periodically chgrp/chmod every file so that the teacher can read and
write it or even move the files elsewhere as well (final submission).

This gives each student complete freedom of choice for filenames as well
as control over the contents of his submission right up until the time
it is collected without the danger of it being overwritten or deleted by
another student.