[java] How do I find what Java version Tomcat6 is using?

Is there a OS command to find what Java version Tomcat6 is using? I need to use a Perl (including system()) command.

I using Linux. Ubuntu and CentOS

Is there something like?

     tomcat6 version

Or you could use the Probe application and just look at its System Info page. Much easier than writing code, and once you start using it you'll never go back to Tomcat Manager.

If tomcat did not start up yet , you can use the command \bin\cataline version to check which JVM will the tomcat use when you start tomcat using bin\startup

In fact ,\bin\cataline version just call the main class of org.apache.catalina.util.ServerInfo , which is located inside the \lib\catalina.jar . The org.apache.catalina.util.ServerInfo gets the JVM Version and JVM Vendor by the following commands:

System.out.println("JVM Version: " +System.getProperty("java.runtime.version"));
System.out.println("JVM Vendor: " +System.getProperty("java.vm.vendor")); 

So , if the tomcat is running , you can create a JSP page that call org.apache.catalina.util.ServerInfo or just simply call the above System.getProperty() to get the JVM Version and Vendor . Deploy this JSP to the running tomcat instance and browse to it to see the result.

Alternatively, you should know which port is the running tomcat instance using . So , you can use the OS command to find which process is listening to this port. For example in the window , you can use the command netstat -aon to find out the process ID of a process that is listening to a particular port . Then go to the window task manager to check the full file path of this process ID belongs to. .The java version can then be determined from that file path.

You can use the Tomcat manager app to find out which JRE and OS versions Tomcat is using. Given a user tomcat with password password with a role of manager:

Tomcat 6:

curl http://tomcat:password@localhost:8080/manager/serverinfo

Tomcat 7/8:

curl http://tomcat:password@localhost:8080/manager/text/serverinfo

Once you have started tomcat simply run the following command at a terminal prompt:

ps -ef | grep tomcat

This will show the process details and indicate which JVM (by folder location) is running tomcat.

/usr/local/tomcat6/bin/catalina.sh version

For Windows, launch cmd prompt and route to the path(usually bin) where you have your tomcat startup script.

C:\opt\isv\tomcat-7.0\grid\bin>version
Using CATALINA_BASE:   "C:\opt\isv\tomcat-7.0\grid"
Using CATALINA_HOME:   "C:\opt\isv\tomcat-7.0\grid"
Using CATALINA_TMPDIR: "C:\opt\isv\tomcat-7.0\grid\temp"
Using JRE_HOME:        "C:\opt\isv\devtools\jdk1.8.0_45"
Using CLASSPATH:       "C:\opt\isv\tomcat-7.0\grid\bin\bootstrap.jar;C:\opt\isv\tomcat-7.0\grid\bin\tomcat-juli.jar"
Server version: Apache Tomcat/7.0.55
Server built:   Jul 18 2014 05:34:04
Server number:  7.0.55.0
OS Name:        Windows 7
OS Version:     6.1
Architecture:   x86
JVM Version:    1.8.0_45-b15
JVM Vendor:     Oracle Corporation
C:\opt\isv\tomcat-7.0\grid\bin>

After installing tomcat, you can choose "configure tomcat" by search in "search programs and files". After clicking on "configure Tomcat", you should give admin permissions and the window opens. Then click on "java" tab. There you can see the JVM and JAVA classpath.

To find it from Windows OS,

1. Open command prompt and change the directory to tomcat/tomee /bin directory.
2. Type catalina.bat version

3. It should print jre version details along with other informative details.

   Using CATALINA_BASE: "C:\User\software\enterprise-server-tome...

   Using CATALINA_HOME: "C:\User\software\enterprise-server-tome...

   Using CATALINA_TMPDIR: "C:\User\software\enterprise-server-tome...

   Using JRE_HOME: "C:\Program Files\Java\jdk1.8.0_25"

   Using CLASSPATH: "C:\User\software\enterprise-server-tome...

   Server version: Apache Tomcat/8.5.11

   Server built: Jan 10 2017 21:02:52 UTC

   Server number: 8.5.11.0

   OS Name: Windows 7

   OS Version: 6.1

   Architecture: amd64

   JVM Version: 1.8.0_25-b18

   JVM Vendor: Oracle Corporation