[Info-vax] Odd BACKUP error: unsupported file structure !

[Steven Schweda]

On Nov 13, 6:42 pm, JF Mezei <jfmezei.spam... at vaxination.ca> wrote:

> When I first ran BACKUP/COMPARE , it issued verification warnings for
> blocks 5 onwards of that file. And now, when I run backup/compare, it
> issues warnings for different files but not the above file.

   Note that BACKUP /COMPARE may look at bytes past the
End-of-File mark, so it's not unusual to get a complaint
about the last block in the file, where DIFFERENCES is happy
about the same two files.

> Right now, I am thinking of using Steven Schweda's ZIP utility [...]

   It's not mine.  I'll admit only to adding some bits, and
changing others.

   Note also that "zip -V" stops at EOF, and so, if BACKUP
/COMPARE looks past EOF, then you may get some last-block
miscompares after Zip+UnZip.  VAX .OBJ files often get this.
("zip -VV" saves all allocated blocks, so it can avoid some
of these BACKUP /COMPARE complaints.)