Comments on: Identifying portrait/landscape in a set of images, with ImageMagick and BASH http://www.bytebot.net/blog/archives/2008/05/28/identifying-portraitlandscape-in-a-set-of-images-with-imagemagick-and-bash A permanent record for what's interesting today - this is my live journal Fri, 21 Nov 2008 07:10:18 +0000 http://wordpress.org/?v=2.6.3 By: scally-cap162 http://www.bytebot.net/blog/archives/2008/05/28/identifying-portraitlandscape-in-a-set-of-images-with-imagemagick-and-bash#comment-136151 scally-cap162 Sat, 20 Sep 2008 14:43:28 +0000 http://www.bytebot.net/blog/?p=824#comment-136151 Whats up? <a href="http://scally-cap.oxyhost.com/index.html" rel="nofollow">savonius turbine</a> <a href="http://scally-cap.oxyhost.com/index.html" rel="nofollow">savonius turbine</a> <a href="http://scally-cap.oxyhost.com/sayula.html" rel="nofollow">sayula</a> <a href="http://scally-cap.oxyhost.com/sayula.html" rel="nofollow">sayula</a> That is my blog. Visit it, please. c U. Whats up?
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]]> By: TimC http://www.bytebot.net/blog/archives/2008/05/28/identifying-portraitlandscape-in-a-set-of-images-with-imagemagick-and-bash#comment-134343 TimC Wed, 28 May 2008 11:01:25 +0000 http://www.bytebot.net/blog/?p=824#comment-134343 use "set -e" at the top of the script, and mkdir -p to not fail if those directories already exist as directories. Then if one of the mkdirs fail because they already exist as a *file*, then the subsequent mvs won't be executed, which is a very good thing, because otherwise you will end up repeatedly mving many files over the top of one file, and thus losing all but the last one of those files. Yes, a colleague has done this running one of my scripts that wasn't defensive enough, without performing the tests I was expecting him to perform first. No, we didn't have backups. (alternatively, I would also consider using the construct 'yes no | mv -i "$source" "$dest", which would negate the suggestion of using set -e, since it will simply refuse to overwrite anything anyway) P.S. Quote your "$i" :) Defensive shell scripting is good, mmmkay? :) use “set -e” at the top of the script, and
mkdir -p to not fail if those directories already exist as directories.

Then if one of the mkdirs fail because they already exist as a *file*, then the subsequent mvs won’t be executed, which is a very good thing, because otherwise you will end up repeatedly mving many files over the top of one file, and thus losing all but the last one of those files. Yes, a colleague has done this running one of my scripts that wasn’t defensive enough, without performing the tests I was expecting him to perform first. No, we didn’t have backups.

(alternatively, I would also consider using the construct
‘yes no | mv -i “$source” “$dest”, which would negate the suggestion of using set -e, since it will simply refuse to overwrite anything anyway)

P.S. Quote your “$i” :)

Defensive shell scripting is good, mmmkay? :)

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