Q:

Are there any command line validation tools for HTML and CSS?

Is anyone aware of command line tools that can validate CSS and/or HTML?
The W3C offers its validators for local installation, with directions to use from the command line, but the installation process is a nightmare for anyone who isn't a seasoned Java developer.
I've searched with Google, but can't find anything.
Ideally I'd like to use a tool (or tools) that I can point at my CSS, and have it report back on any errors. I want it to be local to increase the speed of my debugging cycles.
Ideally, the tools will understand HTML5 and CSS3.

A:

There is tidy for HTML. It's more than a validator: it doesn't only check if your HTML is valid, but also tries to fix it. But you can just look at the errors and warnings and ignore the fix if you want.
I'm not sure how well it works with HTML5, but take a look at Wanted: Command line HTML5 beautifier, there are some parameter suggestions.
For CSS there is CSSTidy (I have never used it though.)
Regarding the W3C validator: if you happen to use debian/ubuntu, the package w3c-markup-validator is in the repositories and very easy to install via package management. Packages for other distos are also  available.
And the W3C CSS validator is available as a jar, which is easy to use:
java -jar css-validator.jar http://www.w3.org/. 

A:

One of the most popular web-based validators is http://validator.nu.  
On their About page, they list a command-line script (written in Python) for validation.

