Using POSIX with Java Modules

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judovana edited this page Apr 25, 2025 · 2 revisions

The jnr-posix library requires reflective access to some core Java classes in order to support several native operations:

The real process ID (pid) inside java.lang.Process
The real file descriptor inside java.io.FileDescriptor

When running on a Java version that limits reflective operations across Java modules, these accesses may fail and cripple other parts of the API.

If you are running with jnr-posix on the normal Java classpath, the following command line flags should open up these packages:

java --add-opens=java.base/sun.nio.ch=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED <rest of command line>

If you run with jnr-posix as a module (using --module-path) change ALL-UNNAMED to org.jnrproject.posix.