If you are using JetBrains editors like IntelliJ IDEA, PhpStorm, WebStorm etc. Use the following settings in Settings > File Watchers.
Convert style.scss
to style.css
set the arguments
--no-cache --update $FileName$:$FileNameWithoutExtension$.css
and output paths to refresh
$FileNameWithoutExtension$.css
Convert style.scss
to compressed style.min.css
set the arguments
--no-cache --update $FileName$:$FileNameWithoutExtension$.min.css --style compressed
and output paths to refresh
$FileNameWithoutExtension$.min.css
If you're using compass:
compass watch --output-style compressed
There are some different way to do that
sass --watch --style=compressed main.scss main.css
or
sass --watch a.scss:a.css --style compressed
or
By Using visual studio code extension live sass compiler
Source: Stackoverflow.com