RFE to re-purpose option --version:<version>

Paul Benedict pbenedict at apache.org
Mon Aug 8 15:51:06 UTC 2016

Dear Committers,

In Java 9, the --version:<version> has been deprecated. The error message
returned to me is:

Error: Specifying an alternate JDK/JRE version is no longer supported.
  The use of the flag '-version:' is no longer valid.
  Please download and execute the appropriate version.
Unrecognized option: -version:9

I am happy with that. This is not a complain on removing that "alternate"

However, I would like to propose bringing back the option with a different
purpose. I would like to use --version:<version> as a validation check. I
want Java to execute ONLY if the version specified matches the actual
platform version. This would be a wonderful help to scripts that require a
particular version of the Java platform, and should fail if the environment
has been accidentally setup with the wrong Java platform version.

java --version:9
java --version:9.1

AFAICT, the only way to do this now is to execute Java twice. Once to pipe
--version to some find/grep command and check return code, and then execute
java again if the check pass. Loading the runtime twice is not optimal,
wouldn't you agree? Yet if you agree to this proposal, it would be a big
win for script writers, I believe.

Opinions please. Thank you.


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