How to find java home

How to find path where jdk installed?

I’ve installed jdk1.7.0.rpm package in RHEL6.
Where I do find the path to execute my first java program?

Hi, Mohammad. It’s not a stupid question, but one that has been answered in several places already — like this or this question.

Just an PS: on MacOS, Java is usually installed at ‘/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home’, where the version number could be different.

4 Answers 4

For your first java program read this tutorial:

Note these commands give different results. If you are interested in the non-symlink path use whereis java.

I don’t really think this answers the question. The java binary gets installed with the JRE, but if you’re doing development you need JDK, which isn’t necessarily installed in which java (which in my case is /usr/bin).

On RHEL7, you can use locate :

and it led me to the /usr/lib/jvm/ directory which contained the directories:

java-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64/ jre/ jre-1.8.0/ jre-1.8.0-openjdk/ jre-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64/ jre-openjdk/ 

Each of these contain a bin/java

To find the full path of the symbolic link use:

This gave me mostly JDK6 even though java -version gave me 1.8. There was one link to the JDK8 folder near the top.

You can list the installed files with

You will see somewhere a bin directory with java executable

But if the JDK RPM was correctly installed you should already find java in you path.

javac MyFirstJavaClass.java 

and if everything compiles

(If you didn’t change anything the current directory . should already be in your class path)

Since this question is RPM specific, rpm is the way to get started (as answered by @Matteo).

-q is short for --query -l is short for --list 

rpm -ql jdk1.8.0_20 | grep "jdk1.8.0_20/bin$" 

Knowing this may be desirable for setting a user or application’s $JAVA_HOME variable. This is often needed when a system has multiple versions of java installed, or multiple distributions of java installed, such as OpenJDK and Oracle/Sun.

$JAVA_HOME Example

In the ~/.bash_profile , or related file ( .bashrc , .zshrc , .cshrc , setenv.sh ), something similar to the below may be used.

JAVA_HOME='/usr/java/jdk1.8.0_20' export JAVA_HOME PATH="$JAVA_HOME/bin:$PATH" export PATH 

If you would like more control over where Java gets installed, such as in /opt , then the tarball can be used instead of the RPM file.

Other similar questions, are asking about how to find any binary or file, in the general case.

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How to Find JAVA_HOME

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1. Introduction

In this quick tutorial, we’ll learn how to find JAVA_HOME on Windows, Mac, and Linux.

As we all know, JAVA_HOME is an environment variable that we commonly use to locate java executables, like java and javac.

2. Windows-Specific Ways to Find JAVA_HOME

If we’re using Windows as the operating system, first we need to open up our command line (cmd) and type:

If JAVA_HOME is defined in our environment, then the above command will print it out.

Or to show the location of the java executable, we can try:

3. macOS and Linux-Specific Ways to Find JAVA_HOME

If we’re using either macOS or Linux, we can open up our terminal and type:

If JAVA_HOME is defined in our environment, then the above command will print it out.

This probably just shows us /usr/bin/java, which really isn’t very helpful since it’s a symbolic link. To unravel this, we’ll use dirname and readlink.

dirname $(dirname $(readlink -f $(which javac)))

$(dirname $(readlink $(which javac)))/java_home

This command prints the currently used java folder.

4. Using Java to Find JAVA_HOME

If we’re able to run java ourselves, then we have a nearly platform-independent way as well:

java -XshowSettings:properties -version

Running this command outputs numerous properties, one of them being java.home.

To parse it though, we’ll still need a platform-specific tool.

For Linux and macOS, we’ll use grep:

java -XshowSettings:properties -version 2>&1 > /dev/null | grep 'java.home' 

For Windows, we’ll use findstr:

java -XshowSettings:properties -version 2>&1 | findstr "java.home"

5. Conclusion

In this brief article, we learned how to find JAVA_HOME on different operating systems.

If this didn’t work though, it’s possible we didn’t set the JAVA_HOME variable properly while installing Java.

Slow MySQL query performance is all too common. Of course it is. A good way to go is, naturally, a dedicated profiler that actually understands the ins and outs of MySQL.

The Jet Profiler was built for MySQL only, so it can do things like real-time query performance, focus on most used tables or most frequent queries, quickly identify performance issues and basically help you optimize your queries.

Critically, it has very minimal impact on your server’s performance, with most of the profiling work done separately — so it needs no server changes, agents or separate services.

Basically, you install the desktop application, connect to your MySQL server, hit the record button, and you’ll have results within minutes:

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How to find java home

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