Recently I found out about an OS X application called LESS.app. It’s basically an app to compile and minify *.less files into *.css files and does it in real-time. I want to know or I can archive the same thing in Ubuntu and how to go about it.

6 Answers 6


Bryan here. Developer of Less.app.

I highly recommend AGAINST using the older version of LESS (the Ruby-based one). Less.js isn't just a javascript port of LESS, it's a ground-up rewrite that improves a ton of stuff, adds support for things that the old Ruby version doesn't have, and increases compiler speed by about 84%.

Rather than install the Ruby gem, install Node.js and run Less.js through Node from the command line. You'll still have all the -watch functionality, but you'll be using Less.js to do it, which means your life will be much better.

Alternately, use Less.js as a script in the website you're creating. This will work for development. When you're done coding, simply copy the CSS that Less.js generates (from your browser's inspector) and place that into a file, add a .css extension, then remove the Less.js script tag from the HTML pages and substitute the CSS file you just created.

Either way, use Less.js.

  • Thanks Bryan, I was not aware of a Less.js compiler other than the one that has to be injected in the page –I suppose a port of Less.app for Ubuntu is out of the question. ;)
    – Mood
    Feb 1, 2011 at 21:03
  • Does less.js work on headless build machines? I'm getting a "ReferenceError: window is not defined" when I try to run it. Jun 27, 2011 at 16:03
  • Note that the ruby version of less now runs off of less.js Jun 27, 2011 at 19:02


Read Bryan's answer. He knows what he's talking about. ;-)

You can just install less.

  1. Install rubygems and less

    sudo apt-get install rubygems
    sudo gem install less
  2. The official documentation remarks:

    To make gem work properly you should write gem's path to PATH add to ~/.bashrc:

     export PATH=/var/lib/gems/1.8/bin:$PATH
  3. You can then use the less compiler by doing

    lessc style.less

I don't think there's a GUI like the one you've linked to. But since it only seems to be a very shallow gui on top of the real less compiler, I don't think you'll have any problems using it directly. Type

lessc --help

to learn how to use it.

If you want your .less files to be automatically compiled every time you change them, you can use the -w option:

~$ lessc test.less -w
* Watching for changes in test.less... Ctrl-C to abort.
: Change detected... * Updated test.css
: Change detected... * Updated test.css

You can put this process in the background by pressing Ctrl+Z and typing bg, and start as many as you like. You can bring them back to the foreground by doing fg, or fg 3 for the third process, to get a list of all of the jobs and their numbers type jobs.

  • Thank you! Right now I use Less.js (bit.ly/9bG1E9) but I’ll give the ruby compiler a try. The GUI isn’t important to me. But what I really like to have is a tool that watch my .less file(s) and compile a .css every time I save changes to my .less file. How it is done, through an app, CLI or an gedit plug-in doesn’t matter to me much.
    – Mood
    Jan 18, 2011 at 23:23
  • @Mood, it does that - I'll add it to the answer. Jan 18, 2011 at 23:50
  • 1
    Wow! Thanks again. That’s exactly what I'm looking for.
    – Mood
    Jan 19, 2011 at 0:32

To my knowledge, ruby less isn't updated enough to even handle the concatenation operator.

For those interested in a solution that compiles .less upon save for non mac platforms using less.js, you can check out this installation guide*. Though the tutorial is geared towards Windows users, I imagine if you can get Node.js on your system, the script itself will function the same.

*Disclaimer: This tutorial is mine. Just thought people might want to see specifically what the poster above meant by "Use Node.js". I wasn't able to find any scripts online for using Node.js to compile LESS upon file save, so I cooked one up and thought I would share it.

  • It's great to have your participation, but this looks odd -- advertising a post on your own site for a Windows solution? Does this add something that the other answers don't?
    – belacqua
    Apr 2, 2011 at 5:06
  • Yes - non ruby, non MacOSX. You can use the less.js script that works with node.js, so non MacOSX users that can get Node.js compiled can enjoy instant .less compilation.
    – user13446
    Apr 2, 2011 at 5:38
  • Getting Node.js running is not hard. Not sure or I followed this article codediesel.com/linux/installing-node-js-on-ubuntu-10-04 but Node.js was set up in no time. Setting up Less.js however had me pulling out some hairs. I figure once you have Node.js running on Ubuntu you can follow the steps in Joseph’s tutorial to get less.js up and running and thus this is a helpful addition to this thread.
    – Mood
    Apr 8, 2011 at 14:43

Under Ubuntu 11.10, you can simply issue a

sudo apt-get install lessc

you can install it the command line compiler in Ubuntu 12.10 as well:

sudo apt-get install node-less

There's also http://koala-app.com/.

http://crunchapp.net/ was my favorite, but we have to thank Adobe for discontinuing AIR for Linux.

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