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NitrOS9 is a modern clone of the original OS-9 operating system used on the . Both OS-9 and NitrOS9 have an EDIT command, a line-based text editor. As far as I know, EDIT works the same in both. Documentation for the EDIT command can be found in the OS-9 Editor/Assembler/Debugger Manual.

One characteristic of EDIT is that exiting the editor using the "Q" command (or its alias ESC) automatically saves your edits:

If input and/or output files were specified on the OS-9 command line when you started the editor, the text in buffer number one would be written to the initial output file, then the remainder of the initial input file would be copied to the output file. After the text has been copied, the editor will be terminated and control will return to the shell.

ibid. p. 1-16

That's great, but what if I've just made a mess of the file, such as an erroneous delete, and now I want to exit EDIT without saving the file? The only way I've found to do this is to turn off or reset the computer.

How can I exit EDIT without saving the file?

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  • Meta discussion about whether NitrOS9 should be on topic: retrocomputing.meta.stackexchange.com/questions/848/… – Wayne Conrad Feb 21 '20 at 19:22
  • Not commenting on meta because that conversation is more general in terms. Specific to this type of question, it would seem to me that the criteria of applicability should be the fact that, although the OS has recently been updated, the question could much more likely be able to be answered in RC.SE, while quite less likely to be able to be answered in SU.SE, SO.SE, etc., as "retro" people are quite more likely to know anything about a legacy operating system(even though recently maintained) than would the general computing community... – Hitek Feb 22 '20 at 2:28
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While I am not familiar with OS9, I did read the linked PDF.

As stated in the question's documentation quote, specifying input and output files upon opening the editor is optional. The edit will only be saved automatically if the input and output files have been previously specified. It also appears that only the output file will be modified, with the input file remaining intact. If you don't like the edits you made that got saved automatically, you could just DEL the new file after exiting the editor, and then try again.

If you do want more control within the edit feature while still initially specifying input and output files, this could be accomplished using the "File Management" and "Buffer Management" features that are documented starting on page 1-21. As it appears based upon the documentation, the buffer is only written to the output file when you enter the "Q" command. You could, before entering the "Q" command, perform any number of operations, including re-editing your file, clearing the buffer, and even reloading the initial original file to start over from scratch, all before the output file ever gets written. The "File Management" features can also be used to modify the input and output file parameters that may have been specified upon startup, so that you can change what the output filename would be before exiting(emphasis added by me):

CREATE OUTPUT FILE

SYNTAX: .WRITE str

This command is used to create a new output file or close the file after it is no longer needed. The file opened replaces the original output file specified on the command line used to call the editor...

...Closing a file previously opened using the .WRITE command also restores the original output file.

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  • This looked promising, but I haven't got it to work yet. Simply using the .WRITE command with a new path did not prevent the edits from being saved. Good point that there are multiple ways to start the editor. The way I use, "EDIT <path>", creates a temporary file to which changes are written, then on exit it replaces the input file with the temporary file. So the original, unchanged file is, unfortunately, gone. – Wayne Conrad Feb 23 '20 at 4:48

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