问题描述:

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

For example, this command executed from Windows' prompt line:

java -version > java_version.txt

leaves the file java_version.txt empty.

EDIT: The same happens with the help printed out after executing java.exe without any parameters.

EDIT: Just out of a sheer curiosity I checked whether it has been always like that and it turned out it actually has. java -version goes to stderr in JDK 1.1.8 and also in JDK 1.2.2, however the outputs of java.exe without any parameters do not.

网友答案:

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 is implemented.

My brief investigation shows that this is inconsistent with how most Linux commands behave ... everything else I've tried uses stdout. However --version / -version options are a convention rather than something required by any standard.


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: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4380614. Note the "Resolution: Wont Fix" ... and the final comment.

网友答案:

The workaround for this problem is:

java -version 2> java_version.txt
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