Source: Linux China
Today, I come to you from reading a comic TurnOff.us "InSide The Linux Kernel". TurnOff.us is a geek comic website, author Daniel Stori drew some very interesting, Web, cloud computing, Linux-related cartoons about the programming language. Reading is one of today's one.
In the beginning, we take a look at the whole picture of the cartoon!
This cartoon is a side view of the house party planing to painting. The use of such a house to represent the Linux kernel.
foundation
As a house, the most important is its foundation, in this image, we have begun to see from the ground from the bottom:
ground (bottom) by the rows of file cabinets, orderly, placed a file cabinet "file" - files on your computer. The upper left corner, there is a chest hanging plate 421 little penguins, which represents the PID (process IDProcess ID) to process 421, which is viewing the document file cabinet, which represents the system which, in one process accesses the file system . In the lower right corner there is a puppy, it is the watchdog watchdog, which represents monitoring of the file system.
Floor (ground floor)
After reading the ground, then we look above ground level, what are the things.
At this level, the most eye-catching than the middle of a mat, many small penguins sitting around the table. This area represents the process table mat.
The upper left corner there is a little penguin, standing, as if to say what this is clearly a patriarchal figure, but it seems to sit around the little penguins are not very obedient - you have a lot to go see God, just keep chatting - "Hey, How about you say, Wow baby (171), he turned around." It represents the Linux kernel initialization (init) process, that is, we often say that the PID for the process 1. Sitting on the table little penguins are in a wait state wait and wait for the task.
Look, mat next to (the process table) also have a dog, it will monitor the status of small penguins (monitoring process), when the small penguins do not listen, it will bark cried.
On the left side of this layer, there is a number plate for the 1341 little penguins, the door, the door reads 80, indicating that the PID for the 1341 little penguins responsible for the reception port 80, that is, we often say that the HTTP (Web site) port. Little Penguin head with a feather, the feather great history, it is the famous Apache HTTP server's Logo. Well, it is this only:
to the right look, we can see that there is still a door marked 21 on the door, but the door seems to look dilapidated, crooked house number above the door and no one guarding. The FTP protocol 21 port looks a bit old, currently with less people than before, so nobody received here.
In their far right of a house number 22 on the very different treatment, but still have a little penguin with sunglasses in guarding, looks cool ah, it is black people uncles? Why a penguin so cool, because the SSH port is port 22, it is a very important port for remote connection, usually remotely through this port, so that people coming in to port scrutiny.
It says 52 of the body, indicating that it is the first 52 little penguins.
In the upper left corner of the picture, there is a downward step. This step is the bottom (foundation) file system, the process can by this stage, to the file system to read the file operation.
In this layer, there is a little penguin who says 217, he was sweating profusely, looking at his watch. The little penguin is timed tasks (Crontab), he would always pay attention to time to see if you want to do a job.
In the middle of the picture, there are two small penguins carrying pipe (PipeLine) walking, a little penguin can put things in my own hands through this pipeline, pass to the back of the little penguins. But how this looks in front of (? M) Penguin tired sweating, but behind the bird (woman?) Penguins seem at ease - Hey, in front of the pants off fast ~
At this level there is another, a small penguin that glass of red wine in his hand, who says 411, looks a bit numerous liquor. It is red wine (Wine) small penguins, it can do (perform) tasks from Windows.
Thermocline
On the floor, there is a thermocline, there are many different screen that says TTY on each screen (which is outside the terminal). For example, enter the leftmost tty4 the "fre" - which is to enter "freshmeat ..." What: d; next to it on normal tty3 tty2 and more, appears to be relatively normal command; tty7 display graphics Ai interface, a graphical interface (X Window) generally on the terminal No. 7; tty5 and tty6 is empty, which means that nobody uses the two terminals. Etc., tty1 it?
tty (terminal) is one external communication channels, but not every process needs tty, certain processes can be (such as ports) to communicate and external, to provide services directly through other means, so this layer not a complete one, just a thermocline.
Well, we have what it fall?
