Say you'd like to run a command when a file changes, automatically.
For example, I'm using this to call the LessCSS compiler when I save the .less file.
i.e. in this example, I'd like to run the following command everytime the style.less file is changed:
lessc src/css/style.less > src/css/style.css
Install the inotify-tools package
sudo apt install inotify-tools
To set up a command to run automatically, we can do this:
while inotifywait -e close_write src/css/style.less; do lessc src/css/style.less > src/css/style.css; done
More generally, the syntax is the following:
while inotifywait -e close_write /my/file; do mycommand; done
Awesome!