RFR: 8330998: System.console() writes to stderr when stdout is redirected [v2]
Bernd
duke at openjdk.org
Mon Apr 29 19:55:07 UTC 2024
On Mon, 29 Apr 2024 14:56:23 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:
>> Consider code like:
>>
>> public class ConsoleTest {
>> public static void main(String... args) {
>> System.console().printf("Hello!");
>> }
>> }
>>
>>
>> When run as:
>>
>> $ java ConsoleTest.java >/dev/null
>>
>>
>> it prints `Hello!` to stderr, instead of to stdout (where it would be redirected).
>>
>> The proposed fix is to simply force the use of stdout. Sadly, this cannot be done solely using JLine configuration, we actually need to change the JLine's code for that.
>>
>> The most tricky part is a test. There are two sub-tests, one effectively testing a case where all of stdin/out/err are redirected, the other is attempting to test the case where stdin is attached to a terminal, while stdout is redirected. The second sub-test using a native functions to create a pty and to attach to it, and should run in a separate VM, as it leaves the VM attached to the terminal.
>
> Jan Lahoda has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
>
> - Merge branch 'master' into JDK-8330998
> - Fixing test.
> - Attempting to stabilize the test.
> - Improving test to really test the redirect while stdin is connected to a terminal.
> - Fixing typo.
> - 8330998: System.console() writes to stderr when stdout is redirected
I think it's a feature when System.console() actually writes to the tty if stdout is redirected. After all it's not System.out. Of course the question is if it should write to stderr or /dev/tty like mechanism..
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PR Comment: https://git.openjdk.org/jdk/pull/18996#issuecomment-2083542510
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