xmllint failing to properly query with xpath without namespaces

I don’t use xmllint, but I think the reason your XPath isn’t working is because your doc.xml file is using a default namespace (http://purl.org/net/ulf/ns/0.4-02).

From what I can see, you have 2 options.

A. Use xmllint in shell mode and declare the namespace with a prefix. You can then use that prefix in your XPath.

    xmllint --shell doc.xml
    / > setns x=http://purl.org/net/ulf/ns/0.4-02
    / > xpath /x:chat

B. Use local-name() to match element names.

    xmllint --xpath /*[local-name()='chat']

You may also want to use namespace-uri()='http://purl.org/net/ulf/ns/0.4-02' along with local-name() so you are sure to return exactly what you are intending to return.