---
title: TabFS
---
[TabFS](https://github.com/osnr/TabFS) is a browser extension that
mounts your browser tabs as a filesystem on your computer.
Out of the box, it supports Chrome and (to a lesser extent[^firefox])
Firefox, on macOS and Linux.[^otherbrowsers]
[^firefox]: because of the absence of the [chrome.debugger API for
extensions](https://developer.chrome.com/docs/extensions/reference/debugger/).
With a bit more plumbing, you could maybe find a way to connect it
to the remote debugging protocol in Firefox and other browsers and
get that second level of functionality that is currently
Chrome-only.
[^otherbrowsers]: It could probably be made to work on other browsers
like Safari and Opera that support the WebExtensions API, and on
Windows using Dokan or WinFUSE/WSL stuff (?), but I haven't looked
into that.
Each of your open tabs is mapped to a folder.
The files inside a tab's folder directly reflect (and can control) the
state of that tab in your browser. (TODO: update as I add more)
This gives you a _ton_ of power, because now you can apply [all the
existing tools](https://twitter.com/rsnous/status/1018570020324962305)
on your computer that already know how to deal with files -- terminal
commands, scripting languages, etc -- and use them to control and
communicate with your browser.
Now you don't need to [code up a browser extension from
scratch](https://twitter.com/rsnous/status/1261392522485526528) every
time you want to do anything. You can write a script that talks to
your browser in, like, a melange of Python and bash, and you can save
it as [a single ordinary
file](https://twitter.com/rsnous/status/1308588645872435202) that you
can run whenever, and it's no different from scripting any other part
of your computer.
## Examples of stuff you can do![^examples]
[^examples]: maybe some of these feel a little more vital and
fleshed-out and urgent than others. the things I actually wanted
to do and reached for vs. the things that satisfy some pedagogical
property (simple to explain, stack on top of the previous example,
...)
(assuming your current directory is the `fs` subdirectory of the git
repo and you have the extension running)
### List the titles of all the tabs you have open
```
$ cat mnt/tabs/by-id/*/title.txt
GitHub
Extensions
TabFS/install.sh at master ยท osnr/TabFS
Alternative Extension Distribution Options - Google Chrome
Web Store Hosting and Updating - Google Chrome
Home / Twitter
...
```
### Cull tabs like any other files
I'm using Dired in Emacs here, but you could use whatever tools you
already feel comfortable managing your files with.
### Close all Stack Overflow tabs
```
$ rm mnt/tabs/by-title/*Stack_Overflow*
```
or (older / more explicit)
```
$ echo remove | tee -a mnt/tabs/by-title/*Stack_Overflow*/control
```
#### btw
(this task, removing all tabs whose titles contain some string, is a
little contrived, but it's not that unrealistic, right?)
(now... how would you do this _without_ TabFS? I honestly have no
idea, off the top of my head. like, how do you even get the titles of
tabs? how do you tell the browser to close them?)
(I looked up the APIs, and, OK, if you're already in a browser
extension, in a 'background script' inside the extension, _and_ your
extension has the `tabs` permission -- this already requires you to
make 2 separate files and hop between your browser and your text
editor to set it all up! -- you can do
[this](https://developer.chrome.com/docs/extensions/reference/tabs/#method-query):
`chrome.tabs.query({}, tabs => chrome.tabs.remove(tabs.filter(tab =>
tab.title.includes('Stack Overflow')).map(tab => tab.id)))`)
(not _terrible_, but look at all that upfront overhead to get it set
up. and it's not all that discoverable. and what if you want to reuse
this later, or plug it into some larger pipeline of tools on your
computer, or give it a visual interface? the jump in complexity once
you need to communicate with anything -- possibly setting up a
WebSocket, setting up handlers and a state machine -- is pretty
horrifying)
(but to be honest, I wouldn't even have conceived of this as a thing I
could do in the first place)
### Save text of all tabs to a file
```
$ cat mnt/tabs/by-id/*/text.txt > text-of-all-tabs.txt
```
### Reload an extension when you edit its source code
Suppose you're working on a Chrome extension (apart from this
one). It's a pain to reload the extension (and possibly affected Web
pages) every time you change its code. There's a [Stack Overflow
post](https://stackoverflow.com/questions/2963260/how-do-i-auto-reload-a-chrome-extension-im-developing)
with ways to automate this, but they're all sort of hacky. You need
yet another extension, or you need to tack weird permissions onto your
work-in-progress extension, and you don't just get a command you can
trigger from your editor or shell to refresh the extension.
TabFS lets you do all this in [an ordinary shell
script](https://github.com/osnr/playgroundize-devtools-protocol/blob/main/go.sh).
You don't have to write any browser-side code at all.
This script turns an extension (this one's title is "Playgroundize
DevTools Protocol") off, then turns it back on, then reloads any tabs
that have the relevant pages open (in this case, I decided it's tabs
whose titles start with "Chrome Dev"):
```
#!/bin/bash -eux
echo false > mnt/extensions/Playg*/enabled
echo true > mnt/extensions/Playg*/enabled
echo reload | tee mnt/tabs/by-title/Chrome_Dev*/control
```
I mapped this script to Ctrl-. in my text editor, and now I just hit
that every time I want to reload my extension code.
### TODO: Live edit a running Web page
(TODO: it would be cool to have a persistent storage story here)
### TODO: Something with live view of variables
two floating windows. watch
mouse position?
### TODO: Import data (JSON or XLS). Persistent storage?
hehehehehehehehehe
import a plotting library too?
## Setup
**disclaimer**: this extension is an experiment. I think it's cool and
useful and provocative, and I usually leave it on, but I make no
promises about functionality or, especially, security. applications
may freeze, your browser may freeze, there may be ways for Web pages
to use the extension to escape and hurt your computer ... In some
sense, the [whole
point](https://twitter.com/rsnous/status/1338932056743546880) of this
extension is to create a gigantic new surface area of communication
between stuff inside your browser and software on the rest of your
computer.
First, install the browser extension.
Then, install the C filesystem.
### 1. Install the browser extension
(I think for Opera or whatever other Chromium-based browser, you could
get it to work, but you'd need to change the native messaging path in
install.sh. Not sure about Safari. maybe Edge too? if you also got
everything to compile for Windows)
#### in Chrome
Go to the [Chrome extensions page](chrome://extensions). Enable
Developer mode (top-right corner).
Load-unpacked the `extension/` folder in this repo.
**Make a note of the extension ID Chrome assigns.** Mine is
`jimpolemfaeckpjijgapgkmolankohgj`. We'll use this later.
#### in Firefox
You'll need to install as a "temporary extension", so it'll only last
in your current FF session. (TODO: is this fixable? signature stuff?)
Go to [about:debugging#/runtime/this-firefox](about:debugging#/runtime/this-firefox).
Load Temporary Add-on...
Choose manifest.json in the extension subfolder of this repo.
### 2. Install the C filesystem
First, make sure you have FUSE and FUSE headers. On Linux, for example,
`sudo apt install libfuse-dev` or equivalent. On macOS, get [FUSE for
macOS](https://osxfuse.github.io/).
Then compile the C filesystem:
```
$ cd fs
$ mkdir mnt
$ make
```
Now install the native messaging host into your browser, so the
extension can launch and talk to the filesystem:
#### Chrome and Chromium
Substitute the extension ID you copied earlier for
`jimpolemfaeckpjijgapgkmolankohgj` in the command below.
```
$ ./install.sh chrome jimpolemfaeckpjijgapgkmolankohgj
```
or
```
$ ./install.sh chromium jimpolemfaeckpjijgapgkmolankohgj
```
### 3. Ready!
Go back to `chrome://extensions` or
`about:debugging#/runtime/this-firefox` and reload the extension.
Now your browser tabs should be mounted in `fs/mnt`!
Open the background page inspector to see the filesystem operations
stream in. (in Chrome, click "background page" next to "Inspect views"
in the extension's entry in the Chrome extensions page; in Firefox,
click "Inspect")
This console is also incredibly helpful for debugging anything that
goes wrong, which probably will happen. (If you get a generic I/O
error at the shell when running a command on TabFS, that probably
means that an exception happened which you can check here.)
(My OS and applications are pretty chatty. They do a lot of
operations, even when I don't feel like I'm actually doing
anything. My sense is that macOS is generally chattier than Linux.)
## Design
- `fs/`: Native FUSE filesystem, written in C
- [`tabfs.c`](https://github.com/osnr/TabFS/tree/master/fs/tabfs.c):
Talks to FUSE, implements fs operations, talks to extension. I
rarely have to change this file; it essentially is just a stub
that forwards everything to the browser extension.
- `extension/`: Browser extension, written in JS
- [`background.js`](https://github.com/osnr/TabFS/tree/master/extension/background.js):
**The most interesting file**. Defines all the synthetic files and
what browser operations they invoke behind the scenes.[^frustrates]
[^frustrates]: it frustrates me that I can't show you, like, a table
of contents for this source file. because it does have a structure
to it! so I feel like the UI for looking at this one file should
be
[custom-tailored](https://twitter.com/rsnous/status/1262956983222591488)
to
[highlight](https://twitter.com/rsnous/status/1262957486262214657)
and exploit that structure. (I wonder what other cases like this
are out there, where ad hoc UI for one file would be useful. like
if you have tangled-but-regular business logic, or the giant
opcode switch statement of an emulator or interpreter.)
I want to link you to a particular route and talk about it here
and also have some kind of
transclusion (without the horrifying mess of making a lot of tiny
separate files). I want to use typesetting and whitespace to set
each route in that file apart, and set them as a whole apart from the utility functions &
default implementations & networking.
My understanding is that when you, for example, `cat
mnt/tabs/by-id/6377/title.txt` in the tab filesystem:
1. `cat` on your computer does a system call `open()` down into macOS
or Linux,
2. macOS/Linux sees that this path is part of a FUSE filesystem, so it
forwards the `open()` to the FUSE kernel module,
3. FUSE forwards it to the `tabfs_open` implementation in our
userspace filesystem in `fs/tabfs.c`,
4. then `tabfs_open` rephrases the request as a JSON string and
forwards it to our browser extension over stdout (['native
messaging'](https://developer.chrome.com/docs/apps/nativeMessaging/)),
6. our browser extension in `extension/background.js` gets the
incoming message; it triggers the route for
`/tabs/by-id/*/title.txt`, which calls the browser extension API
`browser.tabs.get` to get the data about tab ID `6377`, including
its title,
7. so when `cat` does `read()` later, the title can get sent back in
a JSON native message to `tabfs.c` and finally back to FUSE and the
kernel and `cat`.
(very little actual work happened here, tbh. it's all just
marshalling)
TODO: make diagrams?
## License
GPLv3
## things that would be cool to do
- multithreading. the key constraint is that I pass `-s` to
`fuse_main` in `tabfs.c`, which makes everything
single-threaded. but I'm not clear on how much it would improve
performance? maybe a lot, but not sure. maybe workload-dependent?
the extension itself (and the stdin/stdout comm between the fs and
the extension) would still be single-threaded, but you could
interleave requests since most of that stuff is async. like the
screenshot request that takes like half a second, you could do other
stuff while waiting for the browser to get back to you on that (?)
another issue is that _applications_ tend to hang if any
individual request hangs anyway; they're not expecting the
filesystem to be so slow (and to be fair to them, they really have
[no way](https://twitter.com/whitequark/status/1133905587819941888)
to). some of these problems may be inevitable for any FUSE
filesystem, even ones you'd assume are reasonably battle-tested and
well-engineered like sshfs?
- look into support for Firefox / Windows / Safari / etc. best FUSE
equiv for Windows? can you bridge to the remote debugging APIs that
all of them already have to get the augmented functionality? or just
implement it all with JS monkey patching?
- window management. tab management where you can move tabs
- snapshotting (snapshot.html / snapshot.mhtml file)
- fix leaks
- elim unnecessary round-trips / browser API calls
## hmm
- there's a famous (?) paper, [Processes as Files
(1984)](https://lucasvr.gobolinux.org/etc/Killian84-Procfs-USENIX.pdf),
which lays out the case for the `/proc` filesystem. it's very cool!
very elegant in how it reapplies the existing interface of files to
the new domain of Unix processes. but how much do I care about Unix
processes now? most
[programs](https://twitter.com/rsnous/status/1176587656915849218) that
I care about running on my computer these days are Web pages, [not
Unix
processes](https://twitter.com/rsnous/status/1076229968017772544). so
I want to take the approach of `/proc` -- 'expose the stuff you care
about as a filesystem' -- and apply it to something
[modern](https://twitter.com/rsnous/status/1251342095698112512): the
inside of the browser. can we have 'browser tabs as files'?
- there are two 'operating systems' on my computer, the browser and
Unix, and Unix is by far the more accessible and programmable and
cohesive as a computing environment (it has concepts that compose!
shell, processes, files), even though it's arguably the less important
to my daily life. how can the browser take on more of the properties
of Unix?
- it's [way too
hard](https://twitter.com/rsnous/status/1342236988938719232) to make a
browser extension. even 'make an extension' is a bad framing; it
suggests making an extension is a whole Thing, a whole Project. like,
why can't I just take a minute to ask my browser a question or tell it
to automate something? lightness
- a lot of existing uses of these APIs are in an automation context,
if you want to test your code on an automated browser. I'm much more
interested in an interactive, end-user context. augmenting the way I
use my normal browser. that's why this is an extension. it doesn't
require your browser to run in some weird remote debugging mode that
you'd always forget to turn on. it just [stays
running](https://twitter.com/rsnous/status/1340150818553561094)
- open input space -- filesystem. (it reminds me of Screenotate.)
- now you have this whole 'language', this whole toolset, to control
and automate your browser. there's this built-up existing capital
where lots of people and lots of application software and lots of
programming languages ... already know the operations to work with
files
- this project is cool bc i immediately get [a dataset i care
about](https://twitter.com/rsnous/status/1084166291793965056). I
found myself using it 'authentically' pretty quickly -- to clear out
my tabs, to help me develop other things in the browser so I'd have
actions I could trigger from my editor, ...
- stuff that looks cool:
- SQLite. OSQuery
- it has the right idea
- fake filesystems talk
- [rmdir a non-empty
directory](https://twitter.com/rsnous/status/1107427906832089088)
-- when I was thinking if you should be able to `rm by-id/TABID`
even though `TABID` is a folder. I feel like a new OS, something
like Plan 9, should
[generalize](https://twitter.com/rsnous/status/1070830656005988352)
its file I/O APIs just enough to avoid problems like this. like
design them with the disk in mind but also a few concrete cases of
synthetic filesystems, very slow remote filesystems, etc
do you like setting up sockets? I don't