Off the top of my head, and looking at some of the scripts I use, things I might cover (feedback please!) are:
• calling unix commands and IO streams
- using backticks, system, exec, Open3.popen3
- using the PTY library (ships with standard library, good luck with finding any docs...)
- what are STDIN, STDERR and STDOUT anyway?
• how do you make mysql do this and other magic pager tricks:
# mysql> select * FROM languages;
#
# Ruby ▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆ (200/60.06%)
# Java ▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆ (100/30.03%)
# Fortran ▆▆▆▆▆▆ (30/9.01%)
# C# (3/0.90%)
#
# 4 rows in set (0.00 sec)
• using signals for long-running scripts to get status reports, etc
• maybe a bit on command-line option parsing (not too much, is boring)
• batch renaming of files - everyone needs to know how to do this, right?
• what does STDIO.tty? actually mean, is it useful?
• if anyone's interested in MacOS-specific stuff - using pbcoby, osascript, folder actions
• fork/sleep as a poor man's cron
All a bit unix-y. Clearer?
Ben