Lacking Natural Simplicity

I have occasion to edit and build a DocBook 5 document under both macOS Catalina and Fedora 30.

On macOS I've used homebrew to install the docbook, docbook-xsl, and libxslt (for xsltproc), and fop formulas, and changed my PATH to include the directory where brew installed xsltproc. which will then use /usr/local/etc/xml/catalog to find files, in which brew installed links to the docbook schemas and xsl stylesheets.

On Fedora I've used dnf to install the docbook5-schemas, docbook5-style-xsl, and fop packages.

The document builds fine on both OSes, but Emacs doesn't validate properly against the DocBook RELAX NG schemas, because the *.rnc files supplied with Emacs (26.3 on macOS, 26.2 on Fedora) are for DocBook 4. However, Emacs will look at a schemas.xml file in the same directory as the file you are editing to find the *.rnc files. Unfortunately, of course, they have different locations on macOS with brew and on Fedora.

So I wrote a script, generate-schemas-xml, in bash using xmlcatalog to look up the translation for the URI for the RELAX NG compiled schema file and generate the schemas.xml file and substitute the translation into the file:

generate-schemas-xml (Source)

#! /usr/bin/env bash

schema_location="$(xmlcatalog "" "http://docbook.org/xml/5.0/rng/docbookxi.rnc" |
    grep "^file:///" | sed 's#^file://##')"

cat >schemas.xml <<EOF
<locatingRules xmlns="http://thaiopensource.com/ns/locating-rules/1.0">
<namespace ns="http://docbook.org/ns/docbook" uri="$schema_location"/>
</locatingRules>
EOF

Then I had my Makefile generate the schemas.xml file if it was missing.

It was more complicated that I'd have liked, but it does work.