How to generate identically image file after snapshots

Sean glazier sglazier at
Mon Jul 30 16:28:33 UTC 2007

You have to cp the image once the engine interacts with it it is never the
"same" lots of objects get created and destroyed in image start up the
garbage collector runs anything using a clock runs. So if it is a script it
has to be a shell script. Any deployment specific stuff should go in some
config or text file that is read on start up.


-----Original Message-----
From: squeak-dev-bounces at
[mailto:squeak-dev-bounces at] On Behalf Of Martin
Sent: Monday, July 30, 2007 8:32 AM
To: squeak-dev at
Subject: How to generate identically image file after snapshots

Hi All,

We have tried to produce the same (bit identically) image file after two
consecutive snapshots. We start from a base image then, fileIn several files
into it and finally, we just SmalltalkImage current snapshot: true
andQuit: true. We need this to verify the image file generated by a
third-party with a checksum by executing a script.
After trying several ways to get it (even by scripting the fileIn process
and the snapshot), we found that the image files have, beside the timestamp
differences, thousands of other differences and sometimes the snapshots have
also size differeces.
We supose that this kind of issues may occur due to the GC activity.
Are this issues from the way GC process is changing dynamically the memory
bytes? There is a way to inhibite this activity?
Attached are the scripts we use to produce the image files.

Many thanks in advance,
Martin Troielli

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