How do I tidy up an HTML file's indentation in VI?

There's several things that all need to be in place. Just to summarize them all in one location:

Set the following option:

:filetype indent on
:set filetype=html           # abbrev -  :set ft=html
:set smartindent             # abbrev -  :set si

Then either move the cursor to the top of the file and indent to the end: gg =G
Or select the desired text to indent and hit = to indent it.


With filetype indent on inside my .vimrc, Vim indents HTML files quite nicely.

Simple example with a shiftwidth of 2:

<html>
  <body>
    <p>
    text
    </p>
  </body>
</html>

The main problem using the smart indentation is that if the XML (or HTML) sits on one line as it may end up coming back from a curl request then gg=G won't do the trick. Instead I have just experienced a good indentation using tidy directly called from VI:

:!tidy -mi -xml -wrap 0 %

This basically tells VI to call tidy to cleanup an XML file not wrapping the lines to make them fit on the default 68 characters wide lines. I processed a large 29MB XML file and it took 5 or 6 seconds. I guess for an HTML file the command should therefore be:

:!tidy -mi -html -wrap 0 %

As mentioned in comments, tidy is a basic tool which you could find on many base Linux / MacOS systems. Here is the projet's page in case you wish you had it but don't: HTML Tidy.