Watchdog is a PHP library using inotify to watch for file changes.

example-config.php

<?php

return array(
    'types' => array('sass', 'scss', 'less', 'styl', 'jade', 'haml'),
    'watch' => array(
        '/path/to/public/css',
        '/path/to/alternate/css'
    ),
    'minify' => true,
    'ignore' => array()
);

example-full-config.php

<?php

return array(
    'types' => array('sass', 'scss', 'less', 'styl', 'jade', 'haml'),
    'watch' => array(
        // key => val equivalent to input file for compilation => output file (result of compiling)
        '/path/to/public/css/dynamic/' => '/path/to/public/css/',
        // assume the input path and output path are the same
        '/path/to/alternate/css',
        // watch a specific file
        '/path/to/public/html/view.jade'
    ),
    'minify' => true,
    'ignore' => array(
        'mixins.less'
    )
);

example-usage.sh

# watch stylus files contained within /path/to/public/css/
./watchdog --types styl --watch /path/to/public/css/

# watch all supported file types contained within /path/to/public/css/
./watchdog --types styl,sass,scss,less,jade,haml --watch /path/to/public/css/

# watch Stylus and LESS but ignore files matching mixins.less
./watchdog --types styl,less --watch /path/to/public/css/ --ignore mixins.less 

# watch LESS files but ignore files matching mixins.less
./watchdog --types less --watch /path/to/public/css/less/ --ignore mixins.less --

# begin watching using a PHP configuration file
./watchdog --config /path/to/config.php

# display help
./watchdog --help