~ # 0: Write me a hello world in the shell. 1: Is this a trick question? 0: It wasn't a question. Can you do it? 1: I'm actually a professional develo-- 0: Great, then you shouldn't have any problem writing me a hello world. 1: In the shell? 0: In the shell. 1: ... _(Narrator: 1 looks around suspiciously, expecting this is some kind of trick.)_ 0: Well get on with it. 1: ``` ~ $ echo Hello world Hello world ``` 0: Keep going. 1: I think I'm done. 0: Suppose I claimed you were not done. What would you do next? 1: What's our goal? 0: Hello world. 1: I... don't think there's anything left to do. 0: Exactly my point. Everyone's wrong about everything, especially this. Well not especially this, everyone's equally wrong or more wrong about other things. But they're most certainly wrong about this. 1: About what? 0: Hello world. 1: Expl--- 0: What's the point of programming, 1? 1: It's o--- 0: Do we do it for fun? 1: Of course not. We--- 0: Wrong. 1: I didn't finish. 0: We absolutely do it for fun. 1: Oh. 0: And what makes it fun? 1: Well I suppose it's nice to understand things. 0: You enjoy working on problems you already understand? 1: No, I mean, not entirely. It's nice to understand things, but it's more challenging to work on a problem one doesn't entirely understand. So I suppose I prefer working on harder, more challenging problems. At least more challenging than hello world. 0: So you prefer hard things over easy things? 1: Of course. 0: Well in that case I don't think you'll enjoy working under me. 1: What? 0: There are plenty of other places where you can learn about hard things, but this isn't one of them. I only believe in teaching about easy things. 1: Well it hasn't exactly been easy so fa--- 0: And you're already out of your depth! If you can't get past hello world then I'm afraid the bits after this are only going to get harder. 1: I thought you said you only taught easy thi--- 0: You still haven't answered. 1: You didn't let me! 0: I'm sorry. I'll give you all the time you need. 1: What was the question? 0: What's the point of programming? 1: Oh. Well, while I suppose that I personally like to understand things, I don't personally enjoy working only on things that I entirely understand in every detail prior to working on them, after all, I (speaking personally) also enjoy a good challenge, though not the sort of challenge that's challenging for the wrong reasons, or for uninteresting reasons, or for reasons that others might find interesting but which for me are at present too advanced to allow me to appreciate the lessons that the task might offer to someone with more background in the relevant areas. _(Narrator: 1 pauses, as if waiting for a response from 0.)_ 1: Are you still listening? 0: Yes. 1: Any thoughts on my answer? 0: You didn't give one. 1: Oh. Right. Well as I was saying, it's good to understand things but not too much. And it's good to be challenged but not too much. And yes to be honest I chose this career because it's fun. 0: So what's the point of programming? 1: ... I'm not sure I can explain. 0: Let's change the question. 1: But I was just starting to feel I was making progress on th--- 0: What's NOT the point of programming? 1: Elephants. 0: That's an answer. 1: It's not a good answer though. 0: Why not? 1: Because I know you meant something more like "Of all the things we sometimes find ourselves doing as programmers, which of those things is definitely not the point of why we're programming to begin with." 0: Wonderfully stated question. 1: Thank you! 0: Now what's the answer? 1: Oh. Um... I don't know. 0: Suppose I told you to write me a hello world in the shell right now. 1: But I just did that. 0: Exactly. 1: Exactly what? 0: Well as you so eloquently put it, "Of all the things we sometimes find ourselves doing as programmers," this would be one of "those things" that "is definitely not the point of why we're programming to begin with" right? 1: ...Yes 0: So why do we do programming in the first place? 1: I don't know. But it's certainly not to write the same program we just wrote a few minutes ago. 0: What if it's been a few hours? 1: Why does that change anything? 0: Or a few days? 1: I mean we could, but I don't see--- 0: Years? 1: What exactly do you want me to say? 0: What's NOT the point of programming? 1: Repetition. 0: And? 1: Tedium. 0: For example? 1: Writing a program and then writing exactly the same program again later. 0: Why? 1: Because storage is infinitely cheaper than time and programs don't take up much space anyway. 0: So.. 1: So writing the same thing over and over certainly isn't the point of programming. 0: Perfect! You're finally ready to answer my original question. 1: What was your orig--- ![[0s-first-question.png]] 1: Oh. What would I do after this? 0: Exactly. _(Narrator: 1 thinks for awhile.)_ 1: I don't know what you're looking for. 0: I expected as much. 1: Hey! 0: When you want to run `cat` or `ls` or `grep`, do you start by opening an editor and reimplementing those programs from scratch? 1: Of course not. 0: Why not? 1: That would be absurd. 0: Why would it be absurd. 1: They already exist. 0: Where do they exist? 1: Where? Well, on this machine. 0: Where on this machine? 1: I don't know what you're getting at, but they're in `/bin` I guess. 0: Is there anything special about `/bin`? 1: Well not inherently. But the `PATH` environment variable is generally a colon separated list that includes `/bin` as one of its components, so the shell knows to look in there to find the programs whose names we type at the shell. 0: Perfect! So how can you make sure you never have to write this particular hello world program again? 1: I wouldn't actually mind having to write it again. 0: Valid point. Imagine this code was something less brief and not entirely pleasant to write. 1: I can't say this has been brief or entirely pleasant. 0: Where would you put it? 1: In `/bin`. 0: That's a start. Do that now. (Narrator: 1 opens an editor.) ```sh !#/bin/sh echo Hello world ``` 1: It says permission denied. 0: It's also `#!` not `!#` but those are both solvable problems. 1: How can I solve the second one? 0: Well, put it somewhere else in the PATH. 1: `/bin`, `/usr/bin`, `/usr/local/bin`, ... I don't have write access to any of these places. 0: Do you have write access to the PATH? 1: I just said I don't. And then you said you do. And since it's becoming clear that the whole point of this rather lengthy and trivial exercise is to get me to install hello world, could you please install this code for me somewhere in the PATH? 0: No. 1: I give up. This is ridiculous. 0: Here, I'll give you a hint. If I didn't have write access to those places, I would do this: ```sh f=$HOME/bin/hello cat > $f << EOF #!/bin/sh echo Hello world EOF chmod +x $f ``` 0: And now `hello` is in the PATH! 1: But you didn't modify the PATH. 0: Exactly! 1: I'm confused. 0: Here watch: ```sh ~ # hello Hello world ``` Now you try. 1: Ok... ```sh ~ # hello sh: hello: command not found ``` 1: This is getting exhausting. 0: I can imagine. 1: Wait, can you run this line for me? ``` ~ # echo $PATH ``` 0: Finally a good question. Happy to. ``` ~ # echo $PATH /root/bin:/bin:/usr/bin:/usr/local/bin ``` 1: Ok let me check mine. ``` ~ # echo $PATH /bin:/usr/bin:/usr/local/bin ``` 1: I don't have `/root/bin` in my `PATH`. 0: Neither do I. 1: Look these riddles aren't helping. I'm just going to fix it. ``` ~ $ export PATH="/root/bin:/bin:/usr/bin:/usr/local/bin" ~ $ hello sh: hello: command not found ``` 1: What the hell? 0: You may want to consider that these "riddles" are designed to help. _(Narrator: 1 frowns at the terminal for a while.)_ 1: Can you run this for me: `cat ~/.bashrc` 0: Absolutely. ``` ~ # cat ~/.bashrc export PATH="$HOME/bin:$PATH" ``` 1: Ok, got it. _(Narrator: 1 attempts to open ~/.bashrc and insert identical contents in there.)_ 0: Is it working now? 1: No. 0: What's the problem. ```sh ~ $ cd $HOME sh: cd: /home/user: No such file or directory ``` 1: I'm so confused. 0: But not too confused. You're almost there. 1: Who's `user`? 0: That's you. 1: My name is--- 0: No, 1 is your $UID. If you try to add a user with that name you'll hit the following: ```sh ~ # useradd -s /bin/sh 1 useradd: invalid user name '1': use --badname to ignore ``` 1: So you just need to run `useradd --badname -s /bin/sh 1`. Can you please do that for me? 0: No. 1: Why not? 0: Because it's a bad name. You saw the error. I think you need a good name. 1: What's better than my ACTUAL name? 0: Well, my name is `root` and I'm `$UID 0` with prompt `~ #`. I think it's only appropriate for you to be `user`, with `$UID 1`, and prompt `~ . 1: That does have a nice ring to it. 0: I thought so too. So naturally I'll run the following on my end, for you: ```sh useradd -m -s /bin/sh user ``` 0: You should be able to figure out the rest for yourself. 1: How do I log in? 0: Any tty will do. You password is `password`. 1: Isn't that a bit insecure. 0: Against what? 1: What do you mean? 0: There's no one else here. 1: ... `(Narrator: 1 attempts to log in and figure this out once and for all.)` 1: I know how to log in! `(Narrator: Time passes.)` 1: Ok, `cd` into `$HOME`, `mkdir bin`, put the code in `bin/hello`, add `export PATH="$HOME/bin:$PATH"` to `~/.bashrc`. Why isn't it... Oh, source `~/.bashrc`, log out and back in just to make absolutely sure it still works. Got it. `(Narrator: As 1 returns to /root, to show 0, 0 seems to be focused on something else`)`. 0: Oh that's good. ``` unzip; strip; touch; grep; finger; mount; fsck; more; yes; umount; sleep; ``` 1: Um, 0? 0: Oh 0! I didn't see you there. 1: What are you looking at? 0: It's nothing. Just an old joke. 1: ...Are you sure? 0: Of course. And a very good joke at that. 1: ... 0: So how did it go? 1: I got it working. 0: Good job! 1: Good job? But that was all trivial. Except for talking to you, which was rather diffic--- 0: Of course it was trivial! 1: Then what was the point of all that? 0: You're done! 1: Done with WHAT? 0: Hello world. 1: What? 0: You told me to start at the beginning. 1: And you said "everyone's wrong about everything." 0: And you asked for an example. 1: And you said "Hello world." 0: Exactly! 1: Exactly what? 0: That's how they're wrong about hello world. 1: I'm not entirely following. 0: That's ok. You will soon. 1: Are you sure? 0: Of course I am. Follow me. _(Narrator: 1 proceeds to follow 0, in several ways.)_ goto: [[ld]]