path: root/2020/subtitles/emacsconf-2020--30-a-tour-of-vterm--gabriele-bozzola-sbozzolo.vtt

WEBVTT

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Hello and welcome to this talk.

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The title of this talk is a tour of vterm,

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a fast and fully featured terminal emulator

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inside GNU Emacs.

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So let's try to understand what we mean

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with "fast and fully featured."

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To do that we'll compare vterm

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with the packages which are built in Emacs,

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mainly, term.

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So let's jump into the vterm.

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So this is a vterm buffer

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and this is a ansi-term buffer.

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What I'm going to do now is

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first I'm going to prove to you

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what we mean by fast.

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To do that, let me open a large file display on screen--

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a large file, this is about one megabyte of data--

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and let me time that.

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It takes about 0.6 seconds with vterm.

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Let's do the same with with ansi-term.

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Well, we already see the difference.

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So I will use this time to tell you

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what's different, and what is vterm exactly.

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vterm is a terminal emulator

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built on top of an external library.

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The library is called libvterm,

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and is the same library used by Newton

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for their own terminal emulator.

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It's a C library, and this is what gives us

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a lot of good features. First, the speed.

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Time spent here, 0.6, is essentially

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the time that it takes to:

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1. convert the Emacs representation of text

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into the vterm representation of what is a string,

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and 2., into actually displaying that,

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and that can take time

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if there's fontification involved.

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So these are the 0.6 seconds there.

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As we say, in ansi-term, that's much more time.

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It's much slower. So the terminal will feel

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much snappier, much faster.

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But that's not the main benefit or the only benefit

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of using this external library vterm.

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The second big benefit is that

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vterm has support for all the escape codes

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that xterm has support for,

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so vterm is essentially as running xterm

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inside an Emacs buffer. So let's see that.

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For example, let's start by looking

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at the support for colors.

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We have support for all the colors out of the box.

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We don't have to do anything.

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And if we did the same here, well,

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we have only 20 colors.

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There's a way to get all the colors,

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but it's much more involved.

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But this is not where vterm shines.

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We can run all the commands that we want.

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htop, ncdu, everything runs here.

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Also this title, it's a fairly complicated

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manipulation of the window

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and it will not work here.

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It just doesn't work actually.

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Now the terminal is probably messed up. Yes.

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So using this external library

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removes the burden from the developers

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of having to implement support

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for all the escape codes.

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We just use those.

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So in many ways, running vterm

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is running xterm inside Emacs,

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but it's better than that because,

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since this is an Emacs buffer,

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we can enjoy a lot of features from Emacs

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as well as a tighter integration

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with Emacs itself.

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For example, as you see here,

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the title of my buffer is from the directory I'm in.

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So let's go to my tmp.

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The title will change.

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So there's information being exchanged

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between vterm and Emacs.

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And of course, the title is not the only place

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where information is exchanged.

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I can find a file and I will be in the directory

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where my terminal is.

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This feature is also available in ansi-term,

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and it works also on vterm,

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and it follows me. So if I go to tmp,

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I'll get the tmp.

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If I ssh to a remote server,

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it will work also on remote servers as well,

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which is a very nice way to edit files remotely

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while we're working on a shell.

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And second, while vterm is not an Elisp interpreter

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like eshell, what we can do is

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we can still run Emacs functions.

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So for example...

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that requires some configuration.

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vterm command (message "hi")

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as you see there's a "hi" here.

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So what I'm doing is I'm executing

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the Elisp function hi.

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I can drop that and turn it around,

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hash function to run Elisp functions.

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Or another one, find-file, same.

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We call this feature "message passing,"

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and it requires some configuration

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on the Emacs side as well as in the shell side.

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It's important to stress

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what's the nature of vterm.

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For instance, every time I'm sending a key binding,

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it's not immediately clear if my intention is

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to send it to the shell or to Emacs.

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So vterm implements some reasonable defaults,

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but at the moment it's mainly packaged

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to display characters on a screen.

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So for example, if you're using evil,

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the editing commands in evil

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will not work immediately.

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There's some work to be done

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and integration can be improved on that side,

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but sometimes we really want this to behave

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exactly like a Emacs buffer.

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We want to be able to search.

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If I try to get it to search,

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it will not work.

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I will send it to the shell.

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So to do that, we enabled vterm copy mode.

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As you see, copy mode, and now this buffer

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is essentially a fundamental buffer.

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I can move around. I can search.

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So it must have... I can do everything I want.

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And there are additional features.

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For example, I can jump around all the prompts.

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I find this extremely useful,

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because I can copy updates from my programs.

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What I always have to do is

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I have to Google some errors.

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So what I do is I select that

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and I have my keybinding in Emacs conf,

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and I'm Googling what I have to Google.

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So this is very nice and if I...

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now that I have selected something,

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if I just press return,

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I will go back to my normal editing mode

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with the text copied, so I can paste it back.

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So it's a quick way to interact with copy

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and interact with the output of a buffer.

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So finally, let's discuss how to actually use vterm.

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Let's circle back, let's go,

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and let's look at the GitHub repo

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where development is happening.

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vterm is available in MELPA,

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but since it's leveraging the power

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of an external module,

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you must have Emacs compiled

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with support for modules,

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and many distros like Ubuntu, Debian,

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that's not there. So you have to

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get Emacs with support for modules:

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compiling or getting images somewhere else.

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And also, the first time you are going to use this,

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which works only on Mac or GNU Linux systems,

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Emacs will try to find and compile this module,

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so it's important. This requirement is important.

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If you're using Windows, well,

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it's not available and will not work.

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So to conclude, I want to just advertise this page.

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If you have problems, look at the issues

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and open an issue in case.

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We'll try to help you.

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We are very excited about vterm,

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and I think it's a transformative

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terminal experience inside GNU Emacs.