xmllint will return exit code 10 when an XPATH query finds no matches. With the changes in this commit, the script isn't stopped. Instead, it uses an empty value, which is likely to cause the validation checks (further down in the script) to fail.
As per @horazont's feedback:
> You do not need () around the command in an if. I think that causes a subshell to spawn, the effects of which I'm not certain about.
Further Googling suggests that the exit status of a pipeline is that of the most recently executed foreground pipeline, meaning that the exit code can be used directly in conditional statements.
As per @horazont's feedback: `-u` shouts at you if you use an undefined variable (very useful to catch typos)
and `-o pipefail` improves error handling by also failing if any of the commands in a pipe fail.
This adds a simple bash script that checks if a provided file (filename to be provided as first argument) conforms to XEP-0001.
Expected to be executed from the directory that holds all xep XML files.
Requires one argument: the file name of the xep to be validated, eg:
$ tools/validate-xep0001-conformance.sh xep-0010.xml
exit status will be non-zero upon validation failure.
requires: bash, xmllint
