On Thu, Dec 16, 2021 at 06:04:05PM +0000, mick crane wrote: > Is it at all possible that running Perl executable file somehow shares the > same memory as same file opened in vi and they get jumbled?
No. Each process has its own private memory space. Even if you WROTE to the file (via perl or any other program), the editing buffer you've already got opened in vi would not change, until you explicitly tell vi to re-read the file from disk. So when you add the notion of perl somehow ACCIDENTALLY writing to a random file, it's just doubly nonsense. Your problem description so far has been very hard to understand. It's not clear to me WHAT you are seeing, or why you've reached the conclusions that you've reached. I would start by trying to identify the LAYER where the error is occurring. This could be the X (or Wayland?) display system. Or the terminal emulator which uses the display system. Or the editor which uses the terminal emulator. (Hint: it's probably not the editor.) The first thing I'd do, when I see the problem happen again, would be to ask the editor to redraw the contents of the terminal. In vi, this is done by pressing Ctrl-L while in command mode. You should see a very brief flash as the terminal's contents are wiped, and then recreated. Editors have this command because they run on terminals, and terminals were traditionally connected via RS-232 serial lines, either hard-wired inside a building, or with a modem involved. When a modem is involved, there is a phenomenon called "line noise" which frequently causes extra characters to be printed on the terminal wherever the cursor happens to be. You can ignore these for a while, but if they start to accumulate, or if you're especially bothered by them, you just request a screen redraw. If redrawing the screen within the editor fixes the problem, then the problem was most likely extra characters that had been written onto the terminal. At that point, you can try to discover what wrote them, but it might not be easy to do so. Anything with appropriate privileges can open one of your terminals and write to it. This would include any program you're running, but also things like the kernel broadcasting an emergency message to every terminal. (I doubt the latter is the case for you, as you seem to be saying this is a frequent occurrence, and that you don't recognize the unexpected content. Maybe. It's hard to understand what you're saying.) If redrawing the screen doesn't do anything, then I'd try to figure out the nature of the unexpected content. Is it whole characters? Like, could you -- in theory -- run commands from a different terminal which would move the cursor and write characters on the mangled terminal, and get the results that you see? Or is it misplaced pixels, rather than whole characters? Do you see pieces of window manager borders, parts of characters, and stuff like that? If you're seeing pixel-level stuff, that points toward an issue at the X or Wayland level, possibly bogus drivers or firmware. Or even bad hardware. If it's misplaced whole characters, which are not fixed by redrawing the screen within the editor, then that sounds like a bug in your terminal emulator. Another simple test to perform would be to MOVE the window around. Does this change the unexpected content, or does it move around with the window? Be specific and detailed about what you do. Be clear in how you describe things. Otherwise, we can't help you.
