I need to use cron and at in a project that creates and edits files. Can I do this through shell scripts, or do I need to go with awk, perl or c?

More details please- what are you trying to do? The answer to your question so far is "yes".

two assignments: (please not this is just quickly copied as the assignment was given orally)

1) use the at command. set up the at command so that once every hour for one week append on the end of a file the date and the time

2) use the cron command. run cron at 3 am every day of the week to write out the date and time. create a new file for each day of the week. each time it runs use the mail system to mail a notice to yourself at school and home.

so for these types of progs should i use shell or should i invest my time beefing up on a language?

Hm. Interesting assignments. I would do them as perl one-liners myself, because I love perl. And btw, if you know, say bash shell, learning perl is NOT THAT HARD. I came from C++ to perl myself, but was amazed at how easy it was. So.... I suggest looking into perl.

The best books available IMHO are the O'Reilly series- do Learning Perl, Perl Cookbook, and Programming Perl, in that order. Very good books. Well written. And if you have any troubles, just post a question.