Created script linter.sh. Documentation available in its header.
During gradle build, when there's an error, this is what happens:
Arcanist expects the linters to work as in "a line is an error", so I ignore stderr (by forwarding it to /dev/null) and GREP the word 'FAILED' so that every line printed to stdout that does NOT contain the word is ignored (for example, the Gradle script prints the version number of the project). At the end, all is left as a result is the one-liners that only contain the name of the project & the task. This is enough to be sure that the linter will fail if there's an error and display the full name of the task that failed... if you need more information about the failure, you can re-run that single task yourself to get the details.
Of course that's not as perfect as an actual linter written for Arcanist in PHP, but it's pretty good to the point that:
That's not *perfect*, but that's reliable and is good enough that it won't cause any problems.