Check JDK Version on CentOS

JDK Tutorials - Herong's Tutorial Examples

∟Check JDK Version on CentOS

This section provides a tutorial on how to check the version information of the installed JDK packages on CentOS systems.

If you are using a CentOS (Free version of Red Hat Linux ) system, downloading and installing the latest JDK version might be difficult. But you can easily install binary packages of older JDK versions from CentOS central repository.

First check the current version of JDK on my CentOS system:

herong$ java -version
java version "1.7.0_161"
OpenJDK Runtime Environment (rhel-2.6.12.0.el6_9-i386 u161-b00)
OpenJDK Server VM (build 24.161-b00, mixed mode)

herong$ javac -version
-bash: javac: command not found

herong$ which java
/usr/bin/java

herong$ ls -l /usr/bin/java
/usr/bin/java -> /etc/alternatives/java

herong$ ls -l /etc/alternatives/java
/etc/alternatives/java -> /usr/lib/jvm/jre-1.7.0-openjdk/bin/java

herong$ ls -l /usr/lib/jvm
drwxr-xr-x. 2017 java-1.6.0-openjdk-1.6.0.41
drwxr-xr-x. 2017 java-1.7.0-openjdk-1.7.0.161
lrwxrwxrwx. 2017 jre -> /etc/alternatives/jre
lrwxrwxrwx. 2017 jre-1.6.0 -> /etc/alternatives/jre_1.6.0
lrwxrwxrwx. 2017 jre-1.6.0-openjdk -> java-1.6.0-openjdk-1.6.0.41/jre
lrwxrwxrwx. 2017 jre-1.7.0 -> /etc/alternatives/jre_1.7.0
lrwxrwxrwx. 2017 jre-1.7.0-openjdk -> java-1.7.0-openjdk-1.7.0.161/jre
lrwxrwxrwx. 2017 jre-openjdk -> /etc/alternatives/jre_openjdk

Looks like I have only the JRE part of the OpenJDK 1.7 (and 1.6) installed, missing the compiler which is the developer component.

Then check the CentOS version and system architecture:

herong$ arch
i686

herong$ lsb_release -a
LSB Version:	:base-4.0-ia32:base-4.0-noarch:core-4.0-ia32:...
Distributor ID:	CentOS
Description:	CentOS release 6.9 (Final)
Release:	6.9
Codename:	Final