9P (or the Plan 9 Filesystem Protocol or Styx) is a network protocol developed for the Plan 9 from Bell Labs distributed operating system as the means of connecting the components of a Plan 9 system. Files are key objects in Plan 9. They represent windows, network connections, processes, and almost anything else available in the operating system.
9P was revised for the 4th edition of Plan 9 under the name 9P2000 that contained various fundamental improvements. The latest version of the Inferno operating system also uses 9P2000. The Inferno file protocol was originally called Styx, but technically it has always been a variant of 9P.
A server implementation of 9P for Unix, called u9fs, is included in the Plan 9 distribution. A 9P OS X client kernel extension is provided by Mac9P. A kernel client driver for Linux is part of the v9fs project. 9P and its derivatives have also found application in embedded environments, such as the Styx on a Brick project.
Many of Plan 9's applications take the form of 9P file servers. Examples include:
When you ere trained to walk upright, your first words were "I'm sorry." Trick her. Make her think you walk on water. Yeah, trick her! Splash water on your face to make tears. She's just a song in the making. They're all songs in the making. Sometimes we're friends until you forget how to talk. You get drunk, drunk, drunk. Sometimes you're just a slut on the floor crawling in circles, splashing your eyes with water again. Go write a song about that. I get to read how you broke her and hear your songs over and over. You are a lover, but lovers are hunters even when prey falls in their lap. You hunt them down, then cry when they get hurt. They adore you, and you devour them. "Oh no, I'm so sorry. I really am this time. Don't you know that I love you? I'll make it up to you. Please wait and let me tell you a little bit about myself. This is a game. You don't know it, but you're playing now. You lost the first time, but you think you want to play again. So, take a number like a client in an office lobby. Wait your turn; this game has two participants. Wait!"