topic Re: .a extension ?? in Operating System - OpenVMS

.a extension ??

Jimson_1 — Wed, 26 May 2010 11:22:59 GMT

Hi,

Just downloaded some VMS freeware.
Its a single binary file with a file extension of '.a'.

Any ideas what uses this extension.

A compressed format possibly?

Re: .a extension ??

Mike Kier — Wed, 26 May 2010 11:31:14 GMT

It is most likely a Backup saveset intended to be used with @SYS$UPDATE:VMSINSTAL, the installation mechanism that preceded PCSI.

Re: .a extension ??

Jimson_1 — Wed, 26 May 2010 11:46:01 GMT

Yeah, you're right.

The header was corrupted.
After fixing it, I could extract it using BACKUP.

Thanks

JP

Re: .a extension ??

P Muralidhar Kini — Wed, 26 May 2010 12:15:15 GMT

Hi JamesP,

>> Its a single binary file with a file extension of '.a'.
>> Any ideas what uses this extension.
Looks like the file you have downloaded is a VMS Saveset created using the
BACKUP command. There can also be other files belonging to the saveset
with extensions ".B", ".C" and so on. But in this case there is only one
saveset ".A"

TO install, you need to use the command
$@SYS$UPDATE:VMSINSTAL

>> The header was corrupted.
What does this mean ?.
The file was corrupted

Regards,
Murali

Re: .a extension ??

Jimson_1 — Wed, 26 May 2010 12:49:32 GMT

By corrupted I mean, like what happens when a saveset is zipped. The block size gets reset.

I have a script that fixes this.

I built the source to run locally from my environment.

Re: .a extension ??

Hoff — Wed, 26 May 2010 13:00:02 GMT

Murali,

A BACKUP saveset usually (always?) gets corrupted by an ftp download; the attributes get stripped and BACKUP then throws a snit rather than figuring out what happened and fixing the error on the fly.

This proclivity for corruptions is also why OpenVMS files often get protected by zip "-V" or otherwise. (And which often then leads to the "why bother with using BACKUP inside a zip archive" discussion, as that's unnecessary for many cases given that zip "-V" works. Here, with a VMSINSTAL kit, you'd still have BACKUP involved.)

Which is why folks using the reset_backup_saveset_file_attributes.com tool from the Freeware http://decuslib.com/decus/freewarev80/000tools/

This is also why BACKUP /REPAIR got implemented, which is a fairly recent change to BACKUP and somewhat lacking in transparency. But this does mean you don't need to go download reset_backup_saveset_file_attributes.com.

This stuff has been in the OpenVMS FAQ for a decade or more, too; it's a longstanding and common error with BACKUP savesets.

Re: .a extension ??

Hein van den Heuvel — Wed, 26 May 2010 13:02:00 GMT

JamesP>> The header was corrupted.
Murali>> What does this mean ? The file was corrupted

Nit picking / details: the file data surely was just fine. The file META-data, aka file header was incorrect, notably describing the wrong record size.

And in case someone stumbles into this topic after a google:

OpenVMS 8.3 BAckup can fix this with BACKUP/REPAIR. You could adapt KITINSTAL to use that, or unpack - repack the saveset.

James>> By corrupted I mean, like what happens when a saveset is zipped. The block size gets reset.

Right.

James> I have a script that fixes this.

Right, like James indicates, use one of the several tools out there to fix up the file header. I like mine :-)
Hein.

$ type FIXSAVESET.COM
$IF p1.EQS."" THEN INQUIRE p1 "Save set file name ?"
$IF f$search(p1).EQS."" THEN EXIT
$WRITE SYS$OUTPUT " RFM was ", F$FILE(p1,"RFM"), ", MRS = ", -
F$FILE(p1,"MRS"), ", LRL = ", F$FILE(p1,"LRL"), "."
$SET FILE /ATTR=(RFM=FIX, MRS=44, LRL=44) 'p1 ! Easier for DCL
$OPEN/READ file 'p1
$READ file record
$CLOSE file
$mrs = F$CVSI(40*8,32,record)
$WRITE SYS$OUTPUT "Setting blocksize to: ",MRS
$SET FILE /ATTR=(RFM=FIX, MRS='mrs', LRL='mrs') 'p1

Re: .a extension ??

P Muralidhar Kini — Wed, 26 May 2010 13:17:17 GMT

Hoff/Hein,

>> A BACKUP saveset usually (always?) gets corrupted by an ftp download
Thanks to Hoff and Hein for the explanation.
Ahh, how can i forget this.
Even i did hunt for the "reset_backup_saveset_file_attributes.com" a lot
of times because the backup saveset attributes (the record size) got messed
up everytime i did a FTP of those savesets.

>> This is also why BACKUP /REPAIR got implemented, which is a fairly
>> recent change to BACKUP and somewhat lacking in transparency.
This sounds great. i did not know this. For latest version of VMS atleast
we dont need the freeware tool then.

I will also keep a copy of Hein's program with me.
Thanks Hein.

Regards,
Murali