Ubuntu – Compile .less files into .css after every update

command linecompilingcss

I have installed node, and npm. With npm I downloaded less.

And when I do 

lessc styles.less styles.css -x -w

in terminal, it compiles and compresses the code, but doesnt watch the file for changes, since Im expecting LESS to auto compile and refresh the page automatically. So, if I do any changes in my styles.less, every-time I have to go to terminal and enter the command to compile the less css.

Also, the compiler does NOT even show any compile errors.

Please guide me on how to achieve the above. This is my first day with LESS CSS.

Best Answer

Simply put, the -w argument doesn't exist.

$ lessc --help
usage: lessc [option option=parameter ...] <source> [destination]

If source is set to `-' (dash or hyphen-minus), input is read from stdin.

options:
  -h, --help              Print help (this message) and exit.
  --include-path=PATHS    Set include paths. Separated by `:'. Use `;' on Windows.
  -M, --depends           Output a makefile import dependency list to stdout
  --no-color              Disable colorized output.
  --no-ie-compat          Disable IE compatibility checks.
  -l, --lint              Syntax check only (lint).
  -s, --silent            Suppress output of error messages.
  --strict-imports        Force evaluation of imports.
  --verbose               Be verbose.
  -v, --version           Print version number and exit.
  -x, --compress          Compress output by removing some whitespaces.
  --yui-compress          Compress output using ycssmin
  --max-line-len=LINELEN  Max line length used by ycssmin
  -O0, -O1, -O2           Set the parser's optimization level. The lower
                          the number, the less nodes it will create in the
                          tree. This could matter for debugging, or if you
                          want to access the individual nodes in the tree.
  --line-numbers=TYPE     Outputs filename and line numbers.
                          TYPE can be either 'comments', which will output
                          the debug info within comments, 'mediaquery'
                          that will output the information within a fake
                          media query which is compatible with the SASS
                          format, and 'all' which will do both.
  -rp, --rootpath=URL     Set rootpath for url rewriting in relative imports and urls.
                          Works with or without the relative-urls option.
  -ru, --relative-urls    re-write relative urls to the base less file.
  -sm=on|off              Turn on or off strict math, where in strict mode, math
  --strict-math=on|off    requires brackets. This option may default to on and then
                          be removed in the future.
  -su=on|off              Allow mixed units, e.g. 1px+1em or 1px*1px which have units
  --strict-units=on|off   that cannot be represented.

Report bugs to: http://github.com/cloudhead/less.js/issues
Home page: <http://lesscss.org/>

However, you can use inotify to watch for changes and this accomplishes roughly what you want:

while inotifywait -r styles.less; do
    lessc -x styles.less styles.css;
done

2019 update: While lessc is something I still do use directly, occasionally, I tend to lean towards a full webpack stack these days.

It's not quite as soul destroying as it appears from afar, but it can take some time (and trust) to get set up. Especially if you have preconceptions about how this stuff should work.

And yes, I'm sure by Summer 2019 webpack will be a dead project and all the client-side-hipsters will have moved onto something else. That's just the risk here. The good thing is that ultimately this is a layer on top of things like LESS and SASS and various scripting languages, and it's all client side. So you can continue to be a dinosaur for as long as you like.

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