Re: Question about modifying core programs and memory reset after Compile

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Jim Idle

Jul 12, 2022, 7:33:50 PM7/12/22
The answer to these question depends on which version of jBASE you are using. Newer versions have a different mode of compiling, triggered by:

 export JELF=1

In your login profile.

Your subroutines and programs are compiled to machine code and built in to a shared library. If your shell is ssh, and you have called the subroutine once, then the shared library will already be attached to the shell and you need to exit it and come back in. It isn’t because of JED, and the source code won’t help you. It is just your usage pattern changes.

Nobody should be compiling and cataloging in to a live system, but people do, and there are techniques to mitigate for this scenario, but it can be a pain when developing. JELF mode overcomes this, thanks to more modern systems having better capabilities in this regard. It also carries the source code (optionally encrypted) that was used to compile the program - because many MV shops do not use much in the way of version control etc.

As a developer, the best way to get around this is to not use jsh as your login shell. Use zsh and the oh-my-zsh plugin. If you need jsh to run process etc, then you can start it at the command line, do whatever, then just exit with ^d. It is just getting used to a slightly different lifecycle. Again, this should not be needed in JELF mode. 

However, you have not said whether you are on Windows or Linux. If Windows, then learn powershell. When submitting questions, always include the output of the jdiag command.

yum install zsh

Your development experience is much better using a system shell, but be prepared for a few days adjustment. Trying to use an MV shell frustrates the heck out of me.


On Jul 13, 2022 at 4:27:58 AM, Greg Motter <> wrote:
Hi all, Couple of quick questions from someone new to jBase. I have quite a few years of experience on Universe, but not much on jBase and have a couple questions.

1) Is it possible to change the core system programs like it is on Universe. For example can JED be modified to add some custom security? If so which File/Table is that?

2) If I can see the JED code, I'll likely get my answer to this. But why is it when I do a FIBC within JED does it seem to reset the memory and use the new version, but if I simply BASIC and CATALOG a program I need to log out and back in? What would I need to do to avoid the log out and back in?

Have already learned much browsing the backlog of posts here. Thanks much.

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Jim Idle

Jul 12, 2022, 7:35:30 PM7/12/22
That should read “if your shell is jsh.."

Greg Motter

Jul 13, 2022, 10:58:30 AM7/13/22
to jBASE
Thanks for that info. I think I've figured out what will work. I agree that this was more for development and would not want them changed in production immediately.

Any insight into how to modify core programs like JED?


Jim Idle

Jul 15, 2022, 12:10:41 AM7/15/22
You cannot modify such programs, but everything in jBASE is an individual binary program, so you can of course replace any command with your own version. We did give away the source code for JED back in the day. I think programs like that could be open sourced, but I am no longer in charge of jBASE of course… if I ever was 😉


Greg Motter

Jul 15, 2022, 11:27:42 AM7/15/22
to jBASE
Thanks so much Jim.
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