# Shortest code for key-logger

Okay, I propose a shortest-key-logger challenge. As explained by the gentleman at "Are key-logger questions allowed?", strict rules have to be imposed in order to make this challenge valid for PPCG.

1. The key-logger has to run on Windows, Linux or Mac OSX (any programming language is welcome).
2. Upon execution, it has to show the message: "I'm gonna log you" (either in a console or using GUI).
3. The keys that are relevant for logging in this challenge are letters (case is not important) and numbers, all others such as symbols, control keys and whitespace are optional and can be ignored.
4. All relevant key presses that occur during runtime (even when the application is not in focus) have to be saved in a log file that can be read and verified using any text editor (even an esoteric one, as long as I can verify it using that text editor).

Anyone up for it? Whatdayatink?

• "4. [...] saved in a log file" in what format? Apr 3 '16 at 16:23
• Updated my question to specify intended format. Apr 3 '16 at 16:25
• I can easily log what is typed in my program's REPL, is that sufficient or should it work work when I type anything in my browser or any other application too? Apr 3 '16 at 16:30
• Yes, it should work for anything, "even when the application is not in focus". Apr 3 '16 at 16:32
• Can we write a program that runs on mac (AppleScript), if we provide an example gif of it running? Apr 3 '16 at 19:02

This works on Ubuntu, and requires evtest. It picks a device that is a keyboard, and saves evtest's output to the file l. If you want a more formatted output, I can do that with more bytes.
echo I\'m gonna log you
sudo evtest /dev/input/by-path/ls /dev/input/by-path/|grep kbd>l