239 lines
10 KiB
Markdown
239 lines
10 KiB
Markdown
---
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title: Emacs as an operating system
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date: 2016-04-14
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modified: 2016-05-29
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---
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Emacs is sometimes jokingly called a good operating system with a bad
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text editor. Over the last year, I found myself using more and more of
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Emacs, so I decided to try out how much of an operating system it
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is. Of course, operating system here is referring to the programs that
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the user interacts with, although I would love to try out some sort of
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Emacs-based kernel.
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<!--more-->
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# Emacs as a terminal emulator / multiplexer
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Terminals are all about text, and Emacs is all about text as well. Not
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only that, but Emacs is also very good at running other processes and
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interacting with them. It is no surprise, I think, that Emacs works
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well as a terminal emulator.
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Emacs comes out of the box with `shell` and `term`. Both of these
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commands run the shell of your choice, and give you a buffer to
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interact with it. Shell gives you a more emacs-y experience, while
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term overrides all default keymaps to give you a full terminal
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experience.
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To use emacs as a full terminal, you can bind these to a key in your
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window manager. I'm using i3, and my keybinding looks like this:
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```
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bindsym $mod+Shift+Return exec --no-startup-id emacs --eval "(shell)"
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```
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You can also create a desktop file to have a symbol to run this on a
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desktop environment. Try putting the following text in a file at
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`~/.local/share/applications/emacs-terminal.desktop`:
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```
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[Desktop Entry]
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Name=Emacs Terminal
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GenericName=Terminal Emulator
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Comment=Emacs as a terminal emulator.
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Exec=emacs --eval '(shell)'
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Icon=emacs
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Type=Application
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Terminal=false
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StartupWMClass=Emacs
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```
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If you want to use term instead, replace `(shell)` above with `(term "/usr/bin/bash")`.
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A very useful feature of terminal multiplexers is the ability to leave
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the shell running, even after the terminal is closed, or the ssh
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connection has dropped if you are connection over that. Emacs can also
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achieve this with it's server-client mode. To use that, start emacs
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with `emacs --daemon`, and then create a terminal by running
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`emacsclient -c --eval '(shell)'`. Even after you close emacsclient,
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since Emacs itself is still running, you can run the same command
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again to get back to your shell.
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One caveat is that if there is a terminal/shell already running, Emacs
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will automatically open that whenever you try opening a new one. This
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can be a problem if you are using Emacs in server-client mode, or want
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to have multiple terminals in the same window. In that case, you can
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either do `M-x rename-uniquely` to change the name of the existing
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terminal, which will make Emacs create a new one next time, or you can
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add that to hook in your `init.el` to always have that behaviour:
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```lisp
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(add-hook 'shell-mode-hook 'rename-uniquely)
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(add-hook 'term-mode-hook 'rename-uniquely)
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```
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# Emacs as a shell
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Of course, it is not enough that Emacs works as a terminal
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emulator. Why not use Emacs as a shell directly, instead of bash/zsh?
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Emacs has you covered for that too. You can use eshell, which is a
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shell implementation, completely written in Emacs Lisp. All you need
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to do is press `M-x eshell`.
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The upside is that eshell can evaluate and expand lisp expressions, as
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well as redirecting the output to Emacs buffers. The downside is
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however, eshell is not feature complete. It lacks some features such
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as input redirection, and the documentation notes that it is
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inefficient at piping output between programs.
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If you want to use eshell instead of shell or term, you can replace
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`shell` in the examples of terminal emulator section with `eshell`.
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# Emacs as a mail cilent
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[Zawinski's Law](http://www.catb.org/~esr/jargon/html/Z/Zawinskis-Law.html):
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Every program attempts to expand until it can read mail. Of course, it
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would be disappointing for Emacs to not handle mail as well.
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Emacs already ships with some mail capability. To get a full
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experience however, I'd recommend using
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[mu4e](http://www.djcbsoftware.nl/code/mu/mu4e.html) (mu for emacs). I
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have personally set up [OfflineIMAP](http://www.offlineimap.org/) to
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retrieve my emails, and mu4e gives me a nice interface on top of that.
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I'm not going to talk about the configurations of these programs, I'd
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recommend checking out their documentations. Before ending this
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section, I also want to mention
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[mu4e-alert](https://github.com/iqbalansari/mu4e-alert) though.
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# Emacs as a feed reader (RSS/Atom)
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Emacs handles feeds very well too. The packages I'm using here are
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[Elfeed](https://github.com/skeeto/elfeed) and
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[Elfeed goodies](https://github.com/algernon/elfeed-goodies). Emacs
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can even show images in the feeds, so it covers everything I need from
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a feed reader.
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# Emacs as a file manager
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Why use a different program to manage your files when you can use
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Emacs? Emacs ships with dired, as well as image-dired. This gives you
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a file browser, with optional image thumbnail support.
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# Emacs as a document viewer
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Want to read a pdf? Need a program to do a presentation? Again, Emacs.
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Emacs comes with
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[DocView](https://www.gnu.org/software/emacs/manual/html_node/emacs/Document-View.html)
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which has support for PDF, OpenDocument and Microsoft Office files. It
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works surprisingly well.
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Also, [PDF Tools](https://github.com/politza/pdf-tools) brings even
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more PDF viewing capabilities to Emacs, including annotations, text
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search and outline. After installing PDF Tools, Emacs has become my
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primary choice for reading PDF files.
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# Emacs as a browser
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Emacs comes out of box with
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[eww](https://www.gnu.org/software/emacs/manual/html_node/eww/index.html#Top),
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a text-based web browser with support for images as well.
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Honestly, I don't think I'll be using Emacs to browse the web. But
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still, it is nice that the functionality is there.
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# Emacs as a music player
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Emacs can also act as a music player thanks to
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[EMMS](https://www.gnu.org/software/emms/), Emacs MultiMedia
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System. If you are wondering, it doesn't play the music by itself but
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instead uses other players like vlc or mpd.
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It has support for playlists, and can show thumbnails as well. For the
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music types, it supports whatever the players it uses support, which
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means that you can basically use file type.
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# Emacs as a IRC client
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I don't use IRC a lot, but Emacs comes out of the box with support for
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that as well thanks to
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[ERC](https://www.emacswiki.org/emacs?action=browse;oldid=EmacsIrcClient;id=ERC).
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# Emacs as a text editor
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Finally, Emacs also can work well as a text editor.
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Emacs is a pretty fine text editor out of the box, but I want to
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mention some packages here.
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First,
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[multiple cursors](https://github.com/magnars/multiple-cursors.el). Multiple
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cursors mode allows you to edit text at multiple places at the same
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time.
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I also want to mention
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[undo-tree](http://www.dr-qubit.org/emacs.php#undo-tree). It acts like
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a mini revision control system, allowing you to undo and redo without
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ever losing any text.
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Another great mode is
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[iy-go-to-char](https://github.com/doitian/iy-go-to-char). It allows
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you to quickly jump around by going to next/previous occurrances of a
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character. It is very useful when you are trying to move around a
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line.
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[Ace Jump Mode](https://github.com/winterTTr/ace-jump-mode/) allows
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you to jump around the visible buffers. It can jump around based on
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initial characters of words, or jump to specific lines. It can also
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jump from one buffer to another, which is very useful when you have
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several buffers open in your screen.
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Finally, I want to mention [ag.el](https://github.com/Wilfred/ag.el),
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which is an Emacs frontend for the silver searcher. If you don't know
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about ag, it is a replacement for grep that recursively searches
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directories, and has some special handling for projects, and is very
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fast.
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# Emacs as an IDE
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People sometimes compare Emacs to IDE's and complain that a text
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editor such as Emacs doesn't have enough features. What they are
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forgetting, of course, is that Emacs is an operating system, and we
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can have an IDE in it as well.
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There are different packages for every language, so I'll be only
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speaking on language agnostic ones.
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For interacting with git, [magit](http://magit.vc/) is a wonderful
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interface.
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For auto-completion, [Company mode](https://company-mode.github.io/)
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works wonders. I rely heavily on completion while writing code, and
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company mode has support for anything I tried writing.
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If you like having your code checked as you type,
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[flycheck](https://www.flycheck.org/) has you covered. It has support
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for many tools and languages.
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