Post bash quotes

One recurring complaint is that nobody talks about bash quotes on /prog/. So everyone post some bash quotes. A small explanation wouldn't go amiss either.

I'll start us off with a /prog/ related one from the top 100:

<kow`> "There are 10 types of people in the world... those who understand binary and those who don't."
<SpaceRain> That's only 2 types of people, kow.

The joke here is that 10 in binary is actually 2 in base 10. So when kow` mentioned that there were 10 types of people in the world, the "10" was in binary since those who understand that would be able to understand the joke.
<SpaceRain> STUPID

In Bash, whether to use single or double quotes depends on exactly what you want to do, and the differences can trip you up if you're not concentrating. Here's a quick rundown of what each does and when to use them.

Double quotes are the less restrictive option. Within a double-quoted string, the only special characters that are reinterpreted are $, ` (backquote), and (the escape character). Double quotes are useful when using variables (in case the variable uses other special characters), or to avoid whitespace being used to make one argument into two. For example:

message="My commit message"
git commit -m $message

Here, $message will be interpreted as three separate words, so the only part that will be used as the commit message is "My". "commit" and "message" will be treated as files to look for, and the commit will probably fail. Use double quotes to fix this:

message="My commit message"
git commit -m "$message"