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Date:	Wed, 9 Apr 2003 09:17:48 PDT
From:	"Steven Levine" <steve53@earthlink.net >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: Do NOT use zip -u (was: System backup zip suggestions ? Restore)

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In <3E943EC4.DED@peterskye.com>, on 04/09/03
at 08:40 AM, Peter Skye said:

>What is the -g option? It's not on my zip 2.3 help screen.

It's the grow option. You need to read the man page. There are several
little used options that don't appear on the help screen.

>-T is a good idea, thanks. From the help screen I thought this was just
>for a non-encoding run; I didn't realize you could have zip check the
>file integrity at the end of the process.

I've always used them separately out of habit, but I don't see where the
help screen implies that -T can't be used with other switches. I'll have
to check if pkzip allows them to be combined. If not, that's where I
picked up the habit.

>Don't use -u to update a prior backup.

Agreed. I didn't pick up on this one the first time. My backup scripts
don't use this switch either and I always delete, or in some cases, rename
the existing zipfile before rewriting so the -u is effectively a nop. The
delete avoids all the potential problems you describe. The other reason I
don't use -u is because I figured it could possibly slow down the
operation, depending on how the logic is implemented. I also tend to only
use switches that are really needed. I find I make less mistakes that
way.

>With this option, zip won't
>replace a file if it thinks it hasn't changed, but who knows how zip
>determines if a file or its EA's have changed or not.

I'd have to look at the source, but if zip does any EA specific checks at
all, I'd bet it only checks for a change to the EA size. Anything else
would be computationally expensive.

Steven

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"Steven Levine" MR2/ICE 2.35 #10183 Warp4/FP15/14.085_W4
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