Installing xmllint

I had the same problem and it took me two hours to make it work.

1. Download iconv, libxml2, libxmlsec , zlib from ftp://ftp.zlatkovic.com/libxml/
2. Extract the zip file then copy all the files in the bin folder of each download.
3. Paste the files in a folder (mine = XML)
4. Add the 'C:\folderName' (mine = 'C:\XML') in the path system variable. (btw, im using windows 8, for win7 users here's a link http://www.itechtalk.com/thread3595.html) :
   • windows key + r (run window)
   • type control panel then press enter
   • type path in search box
     
   • under System - click edit the system environment variable
   • Under the advanced tab - click environment variables
   • In the System variables look for Path > Edit > add ";C:\folderName"
   • or just type 'path' in search box located in your win8 charms ( I should have thought of that)
5. Make it work (I only type xmllint and I had no idea why I cant see the xmllint window. This is a note for beginners)
   • copy a xml file into the xmllint directory
   • type xmllint --valid --noout fileName.xml
     
     If
     everything's fine, CONGRATS
     Else
     If you also have this warning : failed to load external entity "fileName.xml"
     -- they say its a bug so I downloaded an older version of libxml2 from http://xmlsoft.org/sources/win32/
     OR (I just saw this solution earlier)
     -- assign another folder to your xml files and run xmllint from there.
     In the command window : -cd C:\Users\user name\Documents\XML files
     -once you're inside it, type the xmllint commands e.g. xmllint --valid --noout fileName.xml)

installation:
http://flowingmotion.jojordan.org/2011/10/08/3-steps-to-download-xmllint/ https://supportweb.cs.bham.ac.uk/documentation/tutorials/docsystem/build/tutorials/docbooksys/segmentedhtml/ch03s03.html
bug :
https://bugzilla.redhat.com/show_bug.cgi?id=863166

For users of Chocolatey, installing xmllint is rather simple:

choco install xsltproc

This package contains the xmllint, iconv, xmlcatalog, and xsltproc commands, and any dependencies are installed automatically.

Xmllint is part of libxml2-utils package. To install, on Linux use: apt install libxml2-utils