which java # or readlink -f $(which java) Linux allows multiple JREs side-by-side. Use update-alternatives (Debian/Ubuntu) or manually set JAVA_HOME . Using update-alternatives (Debian/Ubuntu) # List available Java runtimes sudo update-alternatives --config java Manually register a new JRE sudo update-alternatives --install /usr/bin/java java /opt/jre-17/bin/java 1700 Manual JRE Switching (any distro) Set environment variables per user in ~/.bashrc or ~/.profile :
dirname $(dirname $(readlink -f $(which java))) jre linux
java -version Example output (OpenJDK 11): which java # or readlink -f $(which java)