I have found the git source for SerialMonitor (Arduino/app/src/processing/app/*) but unable to find it in the installed Arduino IDE. I am using Ubuntu 20.04 64-bit.

I want to make changes to it, not so much a terminal emulator but just perform simple ASCII control characters like backspace (0x08). Some advice on replacing it would be appreciated too; I guess it involves jar files (I am not a java developer).

I have read elsewhere about (and used) various other terminal-type programs, but of course they stop the IDE from uploading sketches. So not much good for development.

Or if anyone knows of an already-improved Serial Monitor, and how to install it for the IDE, then that could be perfect.


2 Answers 2


You can't just "find and replace" that file.

Java isn't distributed as source code. It's compiled "bytecode" that isn't modifiable by a human.

You would need to download all the source code, make your changes to it, and then recompile it.

Or, simpler: just use a more capable serial terminal program, such as "Putty" or "TeraTerm" in Windows, or "Minicom" or "Screen" on Linux. I have no idea what is available for OS X.

  • 1
    Screen works out of box in OS X too.
    – hcheung
    Commented Sep 16, 2020 at 12:01
  • A) I did mention that jar files could be involved B) Perhaps I'm not human, but I have successfully patched binary distribution images to fix bugs that annoyed me e.g. Copy-protected games to stop diskette wearing out, Ashton Tate/Borland DBase III & IV, C) I HAVE downloaded all the Ardiuno git repository; I though that that was obvious. If I haven't got ALL the source, I'm still prepared to do so. Not only can I run compilers, I write & modify both compilers and decompilers. D) As mentioned, I have and can run more capable terminal programs, BUT THEY STOP THE IDE FROM UPLOADING SKETCHES
    – brewmanz
    Commented Sep 16, 2020 at 23:26
  • The ide is crude and it only provides crude facilities. If you don't like it then write your own. You sound more than capable.
    – Majenko
    Commented Sep 17, 2020 at 6:39

After some searching, I found that Building Arduino - Steps for First Time Setup was good. It was tricky to find; most searches for 'Build Arduino' assume it's a project with an Arduino, rather than the IDE.

By building this way, I could change the source, then inside the build folder run ant run. So, no need to actually know where it goes.

I had a problem with it grumbling about Incorrect IDE installation folder: Your copy of the IDE is installed in a subfolder of your sketchbook. Please move the IDE to another folder. which would have been more useful if it had said WHAT settings needed changing.

It turns out that preferences.txt had a conflict with settings sketchbook.path and runtime.ide.path. I changed sketchbook.path. All is now good.

  • Ah, yes. The anonymous down-voters. Some people just don't want this knowledge shared,
    – brewmanz
    Commented Sep 18, 2020 at 23:21

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