I've always assumed that ifup and ifdown were conditional commands that performed their assigned duties only if the interface device in question was up or down, as the command might be. I was dead wrong. I blame my mistake on being a programmer, rather than being stupid, but it's simply too close to call.

The if in ifup, ifdown, and ifstatus is not a programmer's if -- it's an abbreviation for interface. On the off chance that I'm not the only one who has misunderstood these commands because of their rather iffy names, here's what they really do and how they are used.

Ifup and ifdown are normally hidden from view and used only in scripts run at startup and shutdown time, so why would we care about them? Well, grasshopper, interfaces happen, that's why. Equipment malfunctions may leave you in need of these commands in between power on and power off.

Have you ever lost your connection to the Internet and ended up rebooting in order to restore it? One morning recently, the CAT 5 cable connecting my desktop to my Linksys router was pulled loose by a kitten foraging for Baud knows what behind my monitor. I didn't know that at the time -- all I knew was that my connection to the Internet suddenly stopped responding. I checked the cable modem and the router, but didn't notice the cable that had been pulled loose from the back of the router. If I had known about ifstatus, I could have solved the puzzle at once.

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