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Date: Wed, 20 Jun 2007 07:23:28 -0700 (PDT)
From: Otis Gospodnetic <otis_gospodnetic@yahoo.com>
Subject: snapinstaller safety
To: solr-user@lucene.apache.org
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Message-ID: <206122.11396.qm@web50310.mail.re2.yahoo.com>

Hi,

Looking at src/scripts/snapinstaller more closely, I saw this block of code:

# install using hard links into temporary directory
# remove original index and then atomically copy new one into place
logMessage installing snapshot ${name}
cp -lr ${name}/ ${data_dir}/index.tmp$$
/bin/rm -rf ${data_dir}/index
mv -f ${data_dir}/index.tmp$$ ${data_dir}/index


Is there a technical reason why this wasn't written as:

logMessage installing snapshot ${name}

cp -lr ${name}/ ${data_dir}/index.tmp$$ && \

/bin/rm -rf ${data_dir}/index && \

mv -f ${data_dir}/index.tmp$$ ${data_dir}/index

This feels a little safer to me - I'd hate to have the main index rm -rf-ed if the cp -lr command failed for some reason (e.g. disk full), but maybe Bill Au & Co. have a good reason for not using &&'s.  There may be other places in various scripts that this might be applicable to, but this is the first place I saw the extra safety possibility.

Thanks,
Otis