Installing Java Runtime Environment On Linux X86-64

Java Runtime Environment (JRE) is required to run Java applications on Linux. On x86-64 systems, you have several installation options ranging from open-source to Oracle’s commercial builds.

Install OpenJDK (Recommended)

OpenJDK is the open-source implementation and is available in all major Linux distributions:

# Fedora / RHEL / Rocky Linux
sudo dnf install java-17-openjdk

# Ubuntu / Debian
sudo apt install default-jre

# For a specific version
sudo dnf install java-11-openjdk    # Fedora
sudo apt install openjdk-11-jre     # Ubuntu

Verify the installation:

java -version

Multiple Java Versions

You can install multiple JRE/JDK versions and switch between them:

# Install multiple versions
sudo dnf install java-11-openjdk java-17-openjdk java-21-openjdk

# List installed versions
alternatives --list | grep java

# Switch the default Java version
sudo alternatives --config java

On Ubuntu/Debian:

sudo update-alternatives --config java

Select the version you want from the menu. The change takes effect immediately.

Setting JAVA_HOME

Many Java applications require the JAVA_HOME environment variable. Find your Java installation path:

# Find the Java home directory
readlink -f $(which java) | sed 's:/bin/java::'

Set it in your shell configuration:

# Add to ~/.bashrc or ~/.profile
export JAVA_HOME=/usr/lib/jvm/java-17-openjdk
export PATH=$JAVA_HOME/bin:$PATH

For system-wide configuration, add to /etc/profile.d/java.sh:

echo 'export JAVA_HOME=/usr/lib/jvm/java-17-openjdk' | sudo tee /etc/profile.d/java.sh
source /etc/profile.d/java.sh

Install Oracle JRE

Oracle’s JRE requires manual download and installation:

# Download from Oracle's website
# https://www.oracle.com/java/technologies/downloads/

# Extract and install
tar -xzf jre-17_linux-x64_bin.tar.gz
sudo mv jre-17.* /usr/local/java/

# Add to alternatives
sudo alternatives --install /usr/bin/java java /usr/local/java/jre-17.*/bin/java 1

Note: Oracle JRE has different licensing terms than OpenJDK. For most use cases, OpenJDK is functionally equivalent and doesn’t require a commercial license.

Verify JRE vs JDK

JRE only runs Java applications. JDK (Java Development Kit) includes the compiler and development tools. Check what you have:

# Check if JDK is installed
javac -version

# If "command not found", you have JRE only
# If it shows a version, you have JDK (which includes JRE)

Install the JDK if you need to compile Java code:

sudo dnf install java-17-openjdk-devel    # Fedora
sudo apt install openjdk-17-jdk           # Ubuntu

Testing Your JRE Installation

Create a simple test program:

// Test.java
public class Test {
    public static void main(String[] args) {
        System.out.println("Java is working! Version: " +
            System.getProperty("java.version"));
        System.out.println("JRE home: " +
            System.getProperty("java.home"));
    }
}

# Compile (requires JDK)
javac Test.java

# Run (JRE is sufficient)
java Test

Quick Reference

sudo dnf install java-17-openjdk — Install JRE on Fedora
sudo apt install default-jre — Install JRE on Ubuntu
java -version — Verify installation
alternatives --config java — Switch Java versions
JAVA_HOME=/usr/lib/jvm/java-17-openjdk — Set Java home

Container-Based Java Runtime

For isolated Java environments, use Docker or Podman:

# Run a Java application in a container
podman run --rm -v $(pwd):/app:Z eclipse-temurin:17-jre java -jar /app/myapp.jar

# Build a custom image
FROM eclipse-temurin:17-jre
COPY myapp.jar /app/myapp.jar
ENTRYPOINT ["java", "-jar", "/app/myapp.jar"]

Popular container JRE images:

eclipse-temurin:17-jre — Adoptium Eclipse Temurin (recommended)
amazoncorretto:17 — Amazon Corretto
azul/zulu-openjdk:17-jre — Azul Zulu

These images are regularly updated with security patches and are smaller than full JDK images.

JRE Security Configuration

For security-sensitive deployments, configure the JRE’s security policies:

# Edit Java security policy
sudo nano $JAVA_HOME/conf/security/java.security

# Key settings:
# securerandom.source=file:/dev/urandom  (or /dev/random for stronger entropy)
# jdk.tls.disabledAlgorithms=SSLv3, TLSv1, TLSv1.1  (disable weak protocols)
# jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024  (disable weak signatures)

Check the JRE's crypto strength:

java -XX:+PrintFlagsFinal -version 2>&1 | grep -i crypto

Installing Java Runtime Environment on Linux x86-64