Options in bash scripts

Bash scripting is really very powerful and lets you bolt together many UNIX programs with ease.  Scripts can be made even more powerful by accepting command-line options.  getopts makes this really easy.  There's a nice little tutorial here

Old textbooks

There's something very different about the writing in old science textbooks.  Maybe it's the more formal language and the outdated terminology.  I discovered some old radiometric units today: the foot-candle, the foot-Lambert, the nit and the stilb are particular favourites.