How to enter debug mode in eclipse when launching tomcat from cmd - eclipse

Question

I am using apache-tomcat-8.5.24 and have the workspace in Eclipse configured and tomcat working properly.
I need though to do some debugging, but I dont know how can I enter debug mode in Eclipse with the tomcat running from cmd? I have done it several times in the past but I was always launching tomcat in debug mode from my IDE.

Answer 1

You would have to enable remote debugging on tomcat for which the following catalina property needs to be added in tomcat startup.sh or tomcat.start.sh or wherever you add tomcat startup properties:
CATALINA_OPTS="$CATALINA_OPTS
-agentlib:jdwp=transport=dt_socket,address=8787,server=y,suspend=n"
Then restart tomcat.
After this is done, you need to open eclipse, and to go "Debug --> Debug Configurations -- type in the search box "remote java application", and create new, then select your module/java project which you want to debug and give the port number same as given in the above command (i.e. 8787 in the example above). Then Apply and launch.

Answer 2

While the other answer may solve someones problem, it didnt solve mine. Though the way i followed and solved my problem is:
First you start tomcat (all services up), and then you start the debug mode in eclipse!!!
For tomcat as i use the catalina.bat jpda run to start my tomcat i just edited it and used it as follows:
catalina.bat jpda run - agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n
For eclipse:
1)In Eclipse’s menu, select Run > Debug Configurations…
2)A new Debug Configurations window will appear
3)In the list on the left, select Remote Java Application. Don’t worry
too much about the word “remote” here. It just means that the JVM
process can either be on the local machine or another machine across
the network.
4)Select New in the context menu (you can either right click to see
the option for it, or select the icon above the list)
5)A new Remote Java Application debug configuration window will appear
6)Change the Name field to say “Tomcat (local)”, or the name of your
web application, your choice. The name you put here can be anything,
but shorter is better because the name will show up in menus.
Eclipse Run Configuration for a separate Tomcat JVM
There are at least three subtabs of configuration: Connect, Source,
and Common. Under the Connect subtab, there is a Project field. Select
the Eclipse project that represents the code you want to debug. For
instance, if you want to debug your webapp, select your webapp’s
Eclipse project here.
All of the other default settings should be fine. You should probably
look through the settings to see if you would like to change any
options, just beware of changing settings if you aren’t sure what the
effect will be. Make sure that the port number you’re setting in the
Connect subtab is the same port number you configured your Tomcat
JVM’s debug server to listen on.
Click Apply, then click Debug. At that point, your Eclipse’s debugger
will connect to your Tomcat JVM’s debug server. Next, switch to the
Eclipse Debug perspective. In Eclipse’s menu, select Window > Open
Perspective > Debug.