Make sure you have Windows 10 with the anniversary update or newer.
You can verify this by pressing the winkey + R and type ‘winver’ and hit enter. The anniversary update has buildnr 14393. And make sure that you have the “Bash on Ubuntu on Windows” feature enabled.
Xmllint is not included by default, so you have to install it first.
sudo apt install libxml2-utils
You can read more about xmllint on http://xmlsoft.org/
in order to format a large XML file which has no line breaks you have to use xmllint like this:
xmllint --format input_xml_file.xml > pretty_output_xml_file.xml
You use the format option on the input_xml_file.xml and redirect the output (>) to a new file with the name pretty_output_xml_file.xml
This is a lot faster than opening the file in notepad++ and use the xml plugin to format it.
Hope it helped. Good luck!