Compile .less files into .css after every update

command-line compiling css

22,947

Solution 1

There is now much easier method.

Install NodeJs. And via NPM install less-monitor

https://www.npmjs.org/package/less-monitor

Solution 2

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.

Solution 3

Use less-watch-compiler:

Install globally

$ (sudo) npm install -g less-watch-compiler

Usage without main file

$ less-watch-compiler FOLDER_TO_WATCH FOLDER_TO_OUTPUT

Usage with main file

$ less-watch-compiler FOLDER_TO_WATCH FOLDER_TO_OUTPUT main.less

22,947

STEEL

Updated on September 18, 2022

Comments

STEEL over 1 year
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.
- don.joey over 10 years
  
  Can you rephrase your question title to make it better fit the content of your question?
- int_ua about 10 years
  
  I've edited it.
STEEL over 10 years

Im sorry, but Im using this on simple frontend HTML/css project. it s not Ruby or node.
Oli over 10 years

So? It's just a tool with which to generate your CSS (and in grunt's case, process your assets). It has nothing to do with the production stack.
STEEL over 10 years

I still didnt get you. the WHILE DO Look you have given, where do I add it. I will check grunt soon
Oli over 10 years

That's bash... You'd stick it in a terminal and run it. You can remove the linebreaks if you want.
STEEL over 10 years

Thanks it worked. I just had to install inotify-tools and run your lines. :)
int_ua about 10 years

Four improvement suggestions: why use -r if we are watching a single file? In my case I needed -m too. Why rewrite the file for every event if we can use -e modify? Also, I think it would be better to move -w option note to the end of the answer. I cannot see my edits, not sure if they were rejected, so adding this comment.
int_ua about 10 years

Update: I have to use inotifywait -r -e DELETE_SELF,ATTRIB,MODIFY with Kate editor. -m doesn't work for me.
Mário Lima almost 9 years

Hmm, less-monitor hasn't been updated in 3 years, and assumes you run Windows — the CLI dies on OS X due to Windows-specific line endings.
STEEL almost 9 years

Yes I used to use Windows. This is very old question. I was a noob back then. Now I use grunt and sometimes gulp. Thanks