xmllint : how to validate an XML using a local DTD file

Question

I have a local DTD file test.dtd. Content is :

<!DOCTYPE coord [
<!ELEMENT coord (date)>
<!ELEMENT date (#PCDATA)>
]>

I'd like to validate an XML using xmllint. This XML has no DOCTYPE in it :

<?xml version="1.0" encoding="x-mac-roman"?>
<coord>
    <date>20150312</date>
</coord>

No problem if I insert the DTD block as a 2nd line into a copy of my XML file and use:

xmllint --valid --noout my2.xml

But when I try :

xmllint --loaddtd test.dtd --valid --noout my.xml

xmllint --dtdvalid test.dtd --noout my.xml

both don't work. The outout is :

test.dtd:1: parser error : Content error in the external subset
<!DOCTYPE coord [
^
test.dtd:1: parser error : Content error in the external subset
<!DOCTYPE coord [
^
Could not parse DTD test.dtd

Any idea ? It seems that my XML MUST contain a DOCTYPE line (with SYSTEM keyword) to reference the external DOCTYPE file, that I want to avoid. See : http://www.w3schools.com/dtd/

Is there any solution without modifying the XML ?

Fastidious

What is the output from that command? – Bryology

It looks like something with the DTD is wrong. Isn't it? – Bryology

No because when I insert this DTD text into the XML as it is, it works. Maybe I need an introducing line in the DTD text file ? – Fastidious

Can you show your dtd and xml? – Bryology

ok, I have modified my question to include them. – Fastidious

Answer 1

First of all, external DTDs do not need the <!DOCTYPE preamble - remove it from the DTD file:

<!ELEMENT coord (date)>
<!ELEMENT date (#PCDATA)>

Then, --loaddtd fetches an external DTD, which is not the same as validating against an external DTD. Use the --dtdvalid option as follows:

$ xmllint --noout --dtdvalid test.dtd test.xml

If the XML document is valid, xmllint will not output anything (because of --noout). If you change the DTD to, say:

<!ELEMENT coord (date,other)>
<!ELEMENT date (#PCDATA)>

The output will be

$ xmllint --noout --dtdvalid test.dtd test.xml
test.xml:2: element coord: validity error : Element coord content does not follow the DTD, expecting (date , other), got (date )
Document test.xml does not validate against test.dtd

---

Look for more information on the doc pages of NMT or XMLSoft.

Player

Thanks. But nothing says that "coord" is the root element. – Fastidious

@EricH. If you think about it, you don't need to know which element is the root. The important thing is that you, the author of the DTD, know which element is the root element, and write a rule for it. xmllint starts parsing an XML document at the root, so this rule will be the first to be applied anyway. – Incommode

Working for me. xmllint --noout --dtdvalid test.dtd test.xml – Germiston