Essential Command Line Tools: xmllint

January 31, 2018

command line xml

I currently spend a lot of my time at the command line, so I thought I’d start a series on tools that are essential to my workflow. Some of these will be well known tools, and others less so, but hopefully there’s something useful for everyone!

xmllint

What is it?

xmllint is a command line XML tool.

How do I get it?

It’s built in to MacOS (ships with the libxml2 package) 🎉

Why is it useful?

Do you ever find yourself reading XML formatted like this?

<?xml version="1.0" encoding="UTF-8"?> <shiporder orderid="889923" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="shiporder.xsd"> <orderperson>John Smith</orderperson> <shipto> <name>Ola Nordmann</name> <address>Langgt 23</address> <city>4000 Stavanger</city> <country>Norway</country> </shipto> <item> <title>Empire Burlesque</title> <note>Special Edition</note> <quantity>1</quantity> <price>10.90</price> </item> <item> <title>Hide your heart</title> <quantity>1</quantity> <price>9.90</price> </item> </shiporder>

Example XML taken from W3Schools

Now imagine working on a 100+mb XML file with over 100mil characters… If only we could format the XML nicely, it might be a bit easier to read.

This is where xmllint comes in:

xmllint --format example.xml

<?xml version="1.0" encoding="UTF-8"?>
<shiporder xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" orderid="889923" xsi:noNamespaceSchemaLocation="shiporder.xsd">
  <orderperson>John Smith</orderperson>
  <shipto>
    <name>Ola Nordmann</name>
    <address>Langgt 23</address>
    <city>4000 Stavanger</city>
    <country>Norway</country>
  </shipto>
  <item>
    <title>Empire Burlesque</title>
    <note>Special Edition</note>
    <quantity>1</quantity>
    <price>10.90</price>
  </item>
  <item>
    <title>Hide your heart</title>
    <quantity>1</quantity>
    <price>9.90</price>
  </item>
</shiporder>

Much easier to read!

And of course, since xmllint is used via the command line, you can use all the other tools and tricks available to you to do further processing:

xmllint --format example.xml > formatted.xml  # Write formatted output to new file

xmllint --format example.xml | wc -l  # Get number of lines in the XML document

xmllint --format example.xml | grep -A 3 -B 1 "Hide your heart"  # Find details of item called "Hide your heart"