[OS X / Linux] The good thing about the command line is that it allows us to get things done quickly. The bad thing? You have to memorize the commands by heart and one wrong character can cause the whole command to fail.
Luckily, you can quickly wipe out everything you typed with the shortcut key “Ctrl + u”. When you have typed a wrong command, simply press “Ctrl + u” and the whole command will be wiped.