Missing file system permissions should produce an error message

[gcorbin]

Problem

When the current user account lacks write permissions for some files inside the benchmark directory, JUBE silently ignores resulting errors.

Observed

For example, user A runs a benchmark

jube run config.yaml
jube result bench/

Then user B wants to change the analysis

 # edit analyser/patternsets/result in config.yaml
 jube analyse --update config.yaml bench

When user B does not have write permission to 'analyse.xml' (created by JUBE from user A inside the benchmark directory), the analyse command does not report any error, but of course the 'analyse.xml' is not updated and the result table not changed.

Of course, the immediate solution in this example is that the users fix the file permissions. But a warning or error from JUBE would be nice and prevent some confusion.

Expected

Jube displays an error message ( jube: cannot modify 'bench/000017/analyse.xml': Permission denied, similar to what rm would display if you tried to remove the file) and exits with error.