Chapter 2. Non-interactively selecting a system-wide Red Hat build of OpenJDK version on RHEL

If you have multiple versions of Red Hat build of OpenJDK installed on RHEL, you can select the default Red Hat build of OpenJDK version to use system-wide in a non-interactive way. This is useful for administrators who have root privileges on a Red Hat Enterprise Linux system and need to switch the default Red Hat build of OpenJDK on many systems in an automated way.

Note

If you do not have root privileges, you can select a Red Hat build of OpenJDK version by configuring the JAVA_HOME environment variable.

Prerequisites

  • You must have root privileges on the system.
  • Multiple versions of Red Hat build of OpenJDK were installed using the yum package manager.

Procedure

  1. Select the major Red Hat build of OpenJDK version to switch to. For example, for Red Hat build of OpenJDK 21, use java-17-openjdk.

    # PKG_NAME=java-17-openjdk
    # JAVA_TO_SELECT=$(alternatives --display java | grep "family $PKG_NAME" | cut -d' ' -f1)
    # alternatives --set java $JAVA_TO_SELECT
  2. Verify that the active Red Hat build of OpenJDK version is the one you specified.

    $ java -version
    openjdk version "17" 2021-09-14
    OpenJDK Runtime Environment 21.9 (build 17+35)
    OpenJDK 64-Bit Server VM 21.9 (build 17+35, mixed mode, sharing)