Here are a few basic signs that it might be time to go outside for some fresh air.
You become very, very confused when pressing the "tab" key does not fill in the rest of what you were typing.
The phrase "man mount" does not strike you as particularly odd.
You spill a glass of milk and look about in confusion for the "undo" button.
When on your Windows partition you want to play a game, so you open up a command prompt and start typing "wine C:\Pro..."
You are surprised at the blank look your boss gives you when you attempt to tell him, "sudo give me a raise".
You chuckle at your friend's "joke" when he tells you he's just spent $300 to buy a word processing program from some company called "Microsoft".
You use vi, emacs, or nano to create your resume, an important report for your Boss, and/or your webpage. (This behavior highly encouraged by the Beige Binary Blog.)
You routinely attempt to type "ifconfig" into the windows command line.
You can say the word "fsck" without giggling.
-OR-
You cannot say the word "fsck" without giggling.
Your first step in reading your new book is placing your cat on top of it.
You understood that last joke.
The word "kernel" slips into your conversation with such regularity that someone gets you a bag of popcorn for your birthday.
You consider "man mplayer" to be one of the longest works of non-fiction yet created.
The phrase "killall gnome" does not bring to mind images of a fantasy-world genocide.
Cheers!
-Jeff
http://www.beigebinary.com/you-may-have-been-using-linux-too-much-when
