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Re: Syntax Question...


From: Linda Walsh
Subject: Re: Syntax Question...
Date: Sun, 14 Aug 2011 20:15:41 -0700
User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.8.1.24) Gecko/20100228 Thunderbird/2.0.0.24 Mnenhy/0.7.6.666




` Dennis Williamson wrote:
On Sun, Aug 14, 2011 at 6:31 PM, Linda Walsh <address@hidden> wrote:
please show quote the section
that shows using an variable that holds the name of an array to be used
(and assigned to)....
====
The FAQ covers indirect,
it covers arrays,
but I see no place where it covers the combination.
----
   That's EXACTLY what I said -- it doesn't show anyway to do it, in fact,
it points the the exact problem I've been complaining about is bash's instability in it's extended features. I thought it would be like perl -- stable progression, not
random jumps that break code.

All he's saying is bash "shouldn't" or "can't (with any stability), but used for
anything complex.

   He may be right.

   Personally I think it sucks.

I was very happy with bash's extensions, and their progression -- right up to this last revision, when functionality was removed, and others functionality was broken

-- I USE tabs when typing a program into bash -- not all the time, but
now I can't -- in "single quotes", it tries to expand to all the words in my curdir.

The script I've been working on was suppose to be relatively simple -- but given the all the error checking I've been putting in, and all of the state tracking so a run of the script wouldn't come in and corrupt what had been left by a previous run, it's gotten ALOT more complex.

Conceptually...about 8-10 lines of english, -> almost 1500 lines of bash code -- MUCH of
which is to compensate for bashes new broken features.


One can claim it's my fault for not using POSIX, but I don't have this problem in perl (the python people did...).... maybe I haven't appreciated how stable perl has been -- like C.

But
1) create snapshot
2) look for oldest active snapshot
3) rsync the diffs from the oldest snapshot compared against current to a 'diff vol' 4) create new 'static vol' sized to content on diff vol, and get rid of the oldest active snapshot.


That's. IT!

But...
.9) see if we have already created a snapshot today and require an override flag
3.5) label diff vol  with content label of snapshot this came from.
with labeled diff vol, can remove old active snapshot (which needs to be removed
before creating a new one w/same name & same mount point, but static)...
(could create new vol, and do renames, but would result in >lvm fragmentation). 2.8) before copying to diff dir -- make sure it is the correct mounted file system and
delete it's contents (dependent on there being a "valid snap copy"...)

which doesn't get set until the diff dir is copied to the new static stap and IT gets
a label -- saying that the diff-copy completed successfully.

etc.
etc.
etc...


It's just been growing...
(I didn't come close to listing all the checks that are in there now)...

So conceptually --- looked like a simple shell script.

but...to handle bash's broken error handling, all steps have to be 'interlocked' -- state 'checked' into a file system, and validated before going to the next step.

Otherwise, I end up with more problems than you want to know about.


Please try to be briefer and more on topic in your posts to this list,
by the way.


I'm stopping now.
Maybe not entirely on-topic, but I wasn't the one who started a side conversation by
claiming that the information I needed was on URLxxyz...when it wasn't.

It wasn't obvious from anyone that there was some subtle hint that trying to use bash for things like this was ridiculous (if that's the message I was supposed to get
from reading it).    I may be tending more to to agree....but I honestly
thought bash seemed forwardly stable....with broken compat, being relegated to --posix mode. I'm slow to change when things 'break' -- I'd prefer to try to get them fixed, or fix them, than move-on. I know -- most people just move on...whatever.

Thanks for the clarification (I think?)...







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