I64 8.2 Zip

[Sebastian Bazley]

In the Alpha version of Zip/Unzip:

zip "-V" = save VMS file attributes

whereas

unzip "-V" = retain VMS version numbers

Unzip automatically uses the VMS file attributes if present. [except in some obsolete versions of unzip which don't support the file attributes properly]

==

If you want to minimise the size of a Zip archive, then ideally don't use BACKUP as well - just use zip "-V" on the source files.

If you do need to use BACKUP, then add /NOCRC and /GROUP=0 to reduce the overhead.

[Steven Schweda]

Note that UnZIp -V is not related to Zip -V.

Zip -V preserves RMS file attributes.

UnZip -V retains file version numbers.

UnZip -V makes sense after Zip -w, which
causes Zip to store the file version numbers
in the archive. For example:

alp $ zip test.zip test.html;*
zip warning: first full name: ALP$DKA0:[SMS]TEST.HTML;1
zip warning: second full name: ALP$DKA0:[SMS]TEST.HTML;2
zip warning: name in zip file repeated: test.html

zip error: Invalid command arguments (cannot repeat names in zip file)

alp $ zip -w test.zip test.html;*
adding: TEST.HTML;5 (deflated 34%)
adding: TEST.HTML;4 (deflated 34%)
adding: TEST.HTML;3 (deflated 34%)
adding: TEST.HTML;2 (deflated 34%)
adding: TEST.HTML;1 (deflated 34%)

alp $ set default [.test.x]
alp $ create /dire []

alp $ unzip -V [--]test.zip
Archive: ALP$DKA0:[SMS]TEST.ZIP;1
inflating: test.html;5
inflating: test.html;4
inflating: test.html;3
inflating: test.html;2
inflating: test.html;1

alp $ delete *.*;*

alp $ unzip [--]test.zip
Archive: ALP$DKA0:[SMS]TEST.ZIP;1
inflating: test.html
replace test.html? [y]es, [n]o, [A]ll, [N]one, [r]ename:
[...]

Once an archive has been created with Zip -V,
nothing special needs to be done at UnZip
time to get the file attributes restored.

[Steven Schweda]

As for not using BACKUP, it depends. For
example, SET FILE /ENTER, and Zip will see two
different files, and so on.

"Zip -V -w" is nice, but it's not a good
substitute for BACKUP /IMAGE.

/NOCRC and /GROUP=0 are probably reasonable.
Zip + UnZip will do a simple CRC check.

What could go wrong?

[Steven Schweda]

> Once an archive has been created with Zip -V,
> nothing special needs to be done at UnZip
> time to get the file attributes restored.

That's unless you count running UnZip on a VMS
system as "special", of course.

Restore a "Zip -V" archive on a non-VMS system,
and the more exotic file formats (indexed,
variable-length records, and so on) will
probably look corrupt. Stream_LF and fixed-512
do pretty well.

[Lucinda_1]

All great and helpful answers. The bad news is after all of this, we have decided it is best to remove the drive and take that with us to Houston training since everything is still in test anyway. Not to mention to FTP a 10.5 gig file is time consuming and a bit untrustworthy. Good news is, I have learned much about ZIP. Thanks you all have been great. Wish I had used this forum long ago.

Ms Lucinda Perry