pete@octopus.UUCP (Pete Holzmann) (12/17/85)
Thanks to all who responded to my request for help! Several had good clues
that led me to the correct answer.
Original problem: STAT shows two identically-named files in a directory.
DIR and other directory commands don't. How did it happen? How to
fix?
Suggestions:
1. Don't trust STAT. (*WRONG* STAT was correct. DIR was wrong!)
2. There may be invisible garbage characters in one filename.
(*WRONG, In this case* but that can happen, I know...)
3. Maybe STAT sees a 2-extent file as 2 files? (*WRONG*)
4. A file is in the current user and in the public (user 0) area.
(*WRONG* - That isn't a problem on Molecular, nor on any
CP/M I know of, other than maybe OSM)
5. There are 2 files. The CREATE call doesn't check for existing
files first. (*RIGHT*... But see below!)
SUMMARY:
It is up to the programmer to delete any existing file before using
the CP/M CREATE call. CREATE always makes a new directory entry.
HOWEVER, in MP/M, no previous delete is needed- the CREATE call returns
an error if the file already exists!
It appears that CB-80 assumes you will run programs under MP/M, so it
doesn't bother with the delete. On the Molecular, you can run in either
CP/M mode or MP/M mode. In our case, it turned out that one user had
the MP/M flag turned off, so they were the unknown source of duplicate
filenames.
NOTE that duplicate filenames are an unexpected thing in xP/M, and
different programs treat them differently. For example:
STAT - sees both files
DIR - sees one file
D - sees one file, adding size of both files to get 1 size
PIP - tacks one on to the end of the other (PIP will recombine
the files automatically... maybe it collects all of
the extents before moving anything?)
OPEN call - usually gets the first directory entry in the
system.
MORAL: Watch your CREATES and <C,M>P/M's!
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