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Detecting JRE

Rajendra Gangarde

Joined: Sep 10, 2004
Posts: 7
I am not sure about this topic should be part of this form or not. But Still its related to java.
I have to write a shell script in java that will detect JRE and then start executing application bundled as jar file. Thanks in advance
Jesper de Jong
Java Cowboy
Saloon Keeper

Joined: Aug 16, 2005
Posts: 15087

You can't write shell scripts in Java.

If the user's environment is set up properly, you don't need to do complicated things to detect the JRE. Just run the application with:

java -jar TheJarFile.jar

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Rajendra Gangarde

Joined: Sep 10, 2004
Posts: 7
Sorry, I mean to say I have to write shell script in linux,
Which will
1) detect JRE is installed.
2) then check that required libraries are installed
if not then displays error message or else continue application bundled as jar file.
Hope this makes my question more clear
Chetan Parekh
Ranch Hand

Joined: Sep 16, 2004
Posts: 3640
If you want to check the version of JRE then use
System.getProperty("java.version") .

But if you want to check whether JRE is installed or not, this will not help you.

If you are getting ClassNotFound exception, you can say required library is missing.

But better way to do this would be getting jar list using

// Check your .jar files are there or not.

//Get list of files from the
resultant path and check your .jar files are there or not.

[ September 02, 2005: Message edited by: Chetan Parekh ]

My blood is tested +ve for Java.
Mahesh Rana
Ranch Hand

Joined: Sep 05, 2001
Posts: 139
See if it helps:

jrePresent=ls -1 `which java` | wc -l

if [ $jrePresent = 1 ]

jreBinDirectory=dirname `which java`


I agree. Here's the link:
subject: Detecting JRE
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