Interact with the web, unix style.

Pigshell is a pure client-side Javascript app running in the browser, which presents resources on the web as files. These include public web pages as well as private data in Facebook, Google Drive and Picasa albums. It provides a command line interface to construct pipelines of simple commands to filter, display and copy data.

Pigshell is inspired by Unix philosophy: Everything is a file. Programs should do one thing well. Create tools by stringing together a combination of simpler tools. Like human language, CLIs give us freedom of expression - the ability to generate, using a limited vocabulary, an immense variety of meaningful sentences needed to deal with the immense variety of complex situations thrown up by the environment. In contrast, authoritarian UIs restrict us to a menu of pre-approved cliches, with little scope for novel usage and adaptation beyond the designer's imagination.

Running the psty server on your desktop is strongly recommended. It exposes a local directory for pigshell to use as a /home, serves as a proxy HTTP server, and lets pigshell pipe web data through desktop unix utilities.

Pigshell is under active development. No commands, APIs or interfaces are frozen at this point. We expect to release the sources under the GNU GPLv3 around June 2014. A few basic examples of pigshell usage are given below.

Hello, World

Click on the first example in the sidebar, or type the following at the prompt:

cat http://pigshell.com/sample/life-expectancy.html | table2js -e "table.wikitable tr" foo country data | template -ig /templates/d3-worldmap1

Life expectancy

We got a page from a website, extracted a table, converted it to a list of Javascript objects and fed it to a D3-based template for visualization.

A pigshell pipeline processes streams of objects. Commands should be considered as generator functions yielding objects, composed using the pipe operator. The pipeline starts when the last member (an implicit Stdout) asks the upstream command for an object, which in turn asks its upstream command and so on, until the command at the head reluctantly yields an object. It is processed and "returned" downstream, until it hits Stdout which displays it on the terminal. Stdout has an insatiable appetite for objects, so it asks for one more, and the process continues until a null object, signifying the end of the pipeline, makes its way down. Unlike Unix commands, pigshell commands are not independently executing processes.

Using the Terminal

The terminal should be familiar to Unix/bash users, featuring tab completion, history, and Emacs-style CLI editing shortcuts.

The primary prompt is pig<basename_of_cwd>$. When a command is running, a secondary prompt of > is displayed, which can be used to typeahead commands.

Ctrl-C and Ctrl-Z kill and pause the current foreground command respectively, while Ctrl-B "backgrounds" it (roughly like an Ctrl-Z + bg in bash).

A command sequence (e.g. ls|sum; sleep 10; echo done) issued on the CLI will fill its output area as and when objects are emitted. The prompt associated with a command sequence glows green or amber while it is running or stopped, and on its completion settles to red or black depending on its exit status.

Basic commands

ls, cd, mount, cat work similarly enough to their Unix namesakes to help you explore the system.

The ps command displays a list of running pipelines. To kill a long-running pipeline, use ps to find its PID and kill. You can also stop and start pipelines.

Attaching Data Sources

To attach Facebook, Google Drive, Picasa, click on the corresponding icon under Data Source in the sidebar. Attaching an account automatically mounts associated filesystems under /facebook, /gdrive and /picasa respectively.

Data privacy is assured: pigshell is a pure Javascript app, and data flow happens directly between your browser and data sources like Google and Facebook. No access tokens or user data are ever visible to or stored by the pigshell.com server.

Running the mount command without arguments displays the list of currently mounted filesystems.


Everything is a file. Friends are files too. After attaching your Facebook account,

cd /facebook/friends; ls

will give you a list of your friends.

Where in the world are my friends?

map /facebook/friends/*

Friends map

map is a command which plots files with location attributes on a map. Another way of doing this would be

ls /facebook/friends/ | map

Pigshell passes objects over pipes. In this case, ls emits a stream of file objects, which are consumed by map.

Let's refine the above query: Where are all my male friends?

ls /facebook/friends | grep -f gender "^male" | map

grep is a generic filter command, which may filter either by an object's text representation, or a specific field - in this case, gender.

How many friends do I have?

ls /facebook/friends | sum

Pie chart of relationship status of all female friends

    ls /facebook/friends | grep -f gender "female" | chart -f relationship_status

$HOME sweet $HOME

Get a /home. Download Psty, run it on your desktop:

python psty.py -a -d /some/dir # Run in DESKTOP SHELL (bash), not pigshell

and on pigshell,

mount http://localhost:50937/ /home # Run in PIGSHELL, not desktop

The psty server runs only on Linux and Mac OS at present. Now you can read and write to /home it will be backed by /some/directory. cat images and PDFs stored on your desktop inside /some/directory.

This mount command needs to be typed every time you start or reload the page. To do it automatically,

echo "HOME=/home; mount http://localhost:50937/ $HOME" >/local/rc.sh

/local/rc.sh is a script stored in the browser's LocalStorage and will be invoked every time http://pigshell.com is (re)loaded. You need to create a /local/rc.sh on every browser on which you use pigshell.

Data Movement

Assuming you're running psty, backing up Google Drive to your desktop is as simple as

mkdir /home/drivebackup
cp -rv -X /Trash /gdrive/username@gmail.com /home/drivebackup

More details on using Google Drive with pigshell.

Backing up a Picasa album:

mkdir /home/foo; cp /picasa/foo/* /home/foo

Similarly, creating an album and uploading a bunch of pictures to Picasa:

mkdir /picasa/bar; cp /home/barpics/*JPG /picasa/bar

(note that album creation and uploads to Picasa require psty's proxy services)

Copying random URLs to your desktop also works:

cp -c http://ftp.freebsd.org/pub/FreeBSD/ISO-IMAGES-amd64/10.0/FreeBSD-10.0-RELEASE-amd64-bootonly.iso /home

The -c option continues where it left off, so you can resume interrupted downloads.

If you don't have psty:

  • You can copy the files to /downloads, and it will get to your browser's default download folder. Note that you cannot see anything inside the /downloads directory, it's just a pseudo-target to trigger a browser download. For example,

    cp /picasa/foo/DSC_1290.JPG /downloads
  • Click on Upload Files and select a file or files from your desktop. These files are now visible under the directory /uploads. Use ls to verify that they're there. Now use cp to copy them to the target directory.

    cp /uploads/cat.jpg /gdrive
    cp /uploads/cat.jpg /facebook/me/albums/MyCat/

Data conversion

Most filesystem read() operations generate blobs. It is up to the consuming command to convert incoming data into the type it likes. In the command

cat http://pigshell.com/sample/photos/bchips.jpg

cat returns a blob. The terminal figures out that the blob contains PNG data, and displays it as a canvas. Similarly,

cat http://pigshell.com/sample/clickingofcuthbert.pdf

is detected as a PDF and displayed using pdf.js. In case it could not figure out the contents, it attempts to convert it to text and displays it as the usual control-character porridge (though it is mercifully silent, unlike Unix terminals)

In some cases, you have to manually convert data between stages in the pipeline. For example,

cat http://pigshell.com/sample/README.md | to text | jf 'x.split("\\n")' | sum

implements a poor man's wc: cat returns a blob, to converts it to text, jf splits it into lines, sum counts the number of objects it gets. A cat ... | sum would have returned 1, since only one object (a blob) was presented to sum.

URLs as files

Absolute URLs can be used in most places where a file path is expected. Mounting an HTTP URL exposes all links within that page as directories. To mount arbitrary, non-CORS-enabled URLs, you need to run psty.

mount http://pigshell.com/sample/ /mnt; cd /mnt; ls
cat oslogos.png
cat .
cat . | to text

Processing on the desktop - Wsh

Psty runs a websocket service, effectively converting every Unix utility which uses stdin/stdout into a potential member of the pigshell pipeline. For instance, if you have ImageMagick installed,

cat http://pigshell.com/sample/oslogos.png | wsh /usr/local/bin/convert -implode 1 - - | to -g blob

will grab a png file from the web, pipe it through ImageMagick on the desktop, and display the result in pigshell.


To visualize disk usage in a zoomable treemap,

wsh du /Users/foo | to -g text | template -ig /templates/d3-du-treemap


Note that du of a deep tree may take a while, try with a shallow directory tree first)

Finally, an example from 7 command-line tools for data science. This assumes that you have R and ggplot2 already installed.

cd /home; cp https://raw.github.com/jeroenjanssens/data-science-toolbox/master/tools/Rio .

Rio is a bash script to coax R into running with stdin/stdout.

cat https://raw.github.com/pydata/pandas/master/pandas/tests/data/iris.csv | wsh bash ./Rio -ge 'g+geom_point(aes(x=SepalLength,y=SepalWidth,colour=Name))' | to -g blob


Frequently Asked Questions

  1. What about the privacy of my data?

    Your data stays 100% private. The app is all static files and runs completely as client-side Javascript. The server cannot see any data or access tokens.

  2. What browsers are supported?

    Pigshell should work on most modern browsers. We use Chrome on MacOS as our primary dev/test platform, but Firefox, Safari on MacOS, Chrome and Firefox on Linux, and Chrome on Windows work as well.

    Firefox on Windows and Linux occasionally runs into stack overflows. There is no plan to support IE.

    Nothing on the iPad works currently due to keyboard input issues.

  3. Why does ls | cat in pigshell behave like ls | xargs cat in Unix?

    Pigshell passes objects (rather than opaque data) over the pipe. ls in its normal incarnation emits file objects. cat (and other filter commands) receiving file objects will process them not as text, but as files. You can think of it as an implicit xargs.

    ls -l emits text strings, so ls -l | cat will behave the same on both pigshell and a Unix shell. While initially confusing, this is the more natural behaviour in a web environment thickly populated with structured objects. See the User guide for more details.

  4. I can't see the cursor.

    Long-running or CPU-intensive commands may sometimes freeze the page for a few seconds. It is also possible that keyboard focus has gone elsewhere. Click on the last prompt and focus should return there.

  5. There are two cursors on the screen. What do I do now?

    You probably ran a command which is reading something from standard input, and it has opened up a little line just below its command line with a cursor. You may click on that line to move focus there and enter input. You can use Ctrl-D at the beginning of a new line to signal end of input.

    If it was a mistake, then you can simply click on the latest prompt and continue issuing new commands. You can ignore or kill the old command.

  6. How do I reboot?

    Reload the page. Hold down Shift while reloading may help, clearing your browser cache.

  7. What commands are available?

    Most commands are built-in, while a few are scripts found in /bin. You can see a list of commands using the help command. Help for a specific command like ls may be seen either using ls -h or help ls.

  8. How do I write my own scripts?

    The syntax is close enough to bash, and looking through existing scripts in /bin should give you enough of an idea to start writing your own. A trip to the User Guide is definitely recommended, though.

    The edit command implements a simple, minimal editor using CodeMirror.

    You could also create/edit scripts on your desktop using your favourite editor and run them from somewhere under /home.

  9. How do I store scripts so that they survive a "reboot"?

    The /local filesystem uses the browser's HTML5 localStorage as its backing store. Files stored there will survive a page reload (aka "reboot") Note that localStorage is typically limited to about 5 MB per site, so this is only suitable for saving small files like scripts.

    Much better to keep it inside /home, as this area is backed by your host filesystem.

  10. How do I figure out what attributes a file object contains?

    Use printf -j <file>. Most files have a raw attribute containing all the information returned by the backend API.

  11. How do I make sense of these errors? I get parse error for a line which is most certainly correct. Expected "#", "\n", "\r", "\r\n"? WTF?

    Sorry. Error reporting is still in the "PC Load Letter" era. The line number indicates the beginning of a block which failed to parse. So if you have a long multi-line if construct with an error somewhere in the middle, it will flag the if line as the source of the error.

    The best way right now is to comment out chunks of the block to figure out which one is causing the real trouble.

  12. What data sources are supported, and what operations work on those files?

    • Facebook: Creating new albums, reading (but not editing!) photos, writing new photos. Photos created with Pigshell can be deleted. Reading of posts, writing of text posts.

    • Google Drive: Reading, creating, deleting files.

    • Picasa: Reading and editing of photos. Creating and deleting photos supported if you are running psty, as they need a proxy to duck CORS issues.


The user guide has more detailed coverage of pigshell concepts and the scripting language.


Email us at pigshell@googlegroups.com, dev@pigshell.com or tweet @pigshell