I must be missing something --dtdattr <external DTD resource file>
does not work? Kinda like telling xmllint to use what amounts to an externally defined schema?
No way you can create a temp file with the DTD inlined? You will know exactly what you added, so if it validates, the original was valid, too.
(Workaround zone here. More properly, if there is no way to persuade xmllint to read an external DTD then it's really time to find, or write, a tool which can do that.)
But the sad truth is I won't be able to create temp file as well.
Am just searching for a solution where I the source file would be untouched, no temp files created and if possible to pass the external dtd as an argument to xmllint.