In most Linux and BSD, xmllint is delivered or very easy to install. Xmllint can parse and validate one or more XML files with output as reports. A version for Windows is available, too!

The tiny example XML file:

<?xml version="1.0" encoding="UTF-8"?>
<company>
	<branch lang="de-DE">
		<team id="011">
			<name status="on">Develop</name>
			<size>8</size>
		</team>
	</branch>
	<branch lang="en-US">
		<team id="021">
			<name status="off">Sales</name>
			<size>5</size>
		</team>
		<team id="022">
			<name status="on">QA</name>
			<size>2</size>
		</team>
	</branch>
	<branch lang="de-CH">
		<team id="031">
			<name status="on">Develop</name>
			<size>5</size>
		</team>
		<team id="032">
			<name status="off">Consultant</name>
			<size>3</size>
		</team>
	</branch>
</company>

Usage Examples:

# simple validation
$ xmllint --valid example.xml

# validation but without result tree
$ xmllint --valid --noout example.xml

# validation agains a specific DTD schema
$ xmllint --noout --dtdvalid <URL> example.xml

# again RelaxNG schema
$ xmllint --relaxng <schema> example.xml

# again WXS schema
$ xmllint --schema <schema> example.xml

# again schematron
$ xmllint --schematron <schema> example.xml

Query with xmllint

$ xmllint --shell example.xml

# with cat
/ > cat //name
 -------
<name status="on">Develop</name>
 -------
<name status="off">Sales</name>
 -------
<name status="on">QA</name>
 -------
<name status="on">Develop</name>
 -------
<name status="off">Consultant</name>

# with cat and xpath 
/ > cat //*[contains(*,"Consultant")] 
 -------
<team id="032">
	<name status="off">Consultant</name>
	<size>3</size>
</team>

# with grep
/ > grep QA
/company/branch[2]/team[2]/name : ta-        2 QA

# exit
/ > exit

XPath with xmllint

# by root element
$ xmllint --xpath //company example.xml

# by child elements
$ xmllint --xpath //name example.xml 

# by specific child element
$ xmllint --xpath //branch[3] example.xml

# by last child element
$ xmllint --xpath '/company/branch[last()]' example.xml

# path expression
$ xmllint --xpath 'child::*/child::*/team' example.xml

# by attribute
$ xmllint --xpath '//branch[@lang="de-CH"]' example.xml