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.