john pitman wrote:

> Surely qedit doesn't rewrite back over original files and get EOF errors?

I am not sure about QEDIT, but EDITOR.PUB.SYS creates a new file when
performing the KEEP command (as can be seen with LISTF,3 timestamps).


> So why should vi be so dumb, or is it purely
> ux code compile for mpe, and assumes a ux file structure?

I have never seen the hp source code for vi, but I would guess that
it is pretty close to the "unix source" with only minimal changes for
the MPE environment. So it basically sees the OS through "Posix view"
of the world. It is not aware of records or MPE numbered files and
all these things.

If it were the Open Source version, one could sit down and enhance it,
but I doubt that we'll quickly find someone who feels enough desire to
do so as there are other editors to choose from ;-)


> I can understand it not knowing about VA files and the
 > implied record length data in front, but the other stuff?

As I said, things like record size, file limit or those MPE
numbered files with line numbers "hidden" in the last couple
of columns... not known by /bin/vi.

The MPE fixed record text file does not have any line delimiters
in the file, just records padded to proper length. However, what
vi expects (and sees due to file system's bytestream emulation
layer) is a sequence of lines delimited by LF chars.

When writing back to the file, the file system takes care of
stripping the LF chars and padding with blanks to fill records
properly.


Lars.

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