Why does 'java -version' go to stderr?

Is there any special reason for the results of java -version going to stderr?

AFAIK, there is no special reason. It is just how the java command was / is implemented. Probably all the way back to Java 1.0, though it would be very difficult to verify that.

My brief investigation shows that this behavior is inconsistent with how most Linux commands behave ... everything else I've tried uses stdout for version information. (After all, the version information is not "error" output.)

Note however --version / -version options are a convention rather than something required by any formal standard. (The GNU coding standards state that commands should implement --version and that version info should be written to standard output. But POSIX standards don't mention this, nor do the LSB standards.)

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What can / should you do?

• It should be easy to capture stderr instead of stdout in your shell script or batch file.
• There shouldn't be any risk in doing this. Oracle cannot change the Java tool chains to send -version output to stdout without potentially breaking customer scripts. This is highly unlikely¹.

^{1 - Here is evidence of just how unlikely it is: https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4380614. Note the "Resolution: Wont Fix" ... and the final comment.}

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UPDATE

In Java 9, they introduced some new "version" command line options. If you run java -help 2>&1 | grep version against a Java 11 installation you will see the following:

$ java -help 2>&1 | grep version
    -version      print product version to the error stream and exit
    --version     print product version to the output stream and exit
    -showversion  print product version to the error stream and continue
    --show-version
                  print product version to the output stream and continue.

So if you are using Java 11 LTS or later, the solution will be to use --version rather that -version to get the version information.

The workaround for this problem is:

java -version 2> java_version.txt