Bash script to create EXIF information caption

My bash shell scripting has gotten very rusty lately (and ugly), but it’s still good enough to have some fun. For my photo site I need a short program which creates a description string like "Shot with Canon PowerShot S3 IS at 63.9 mm (383.4 mm), 1/320 s, 100, Matrix, F3.5, Auto" from an image. Some shell scripting later I was done.

#!/bin/bash

DIR=$1
rm -rf $DIR/exif
mkdir $DIR/exif

for file in $DIR/*.JPG
do
file=`basename ${file}`
filename=${file/.JPG/}
output=${filename}_EXIF.txt
exiv2 $DIR/$file | awk '
 BEGIN{FS=":"}
 /model/{ model=$2}
 /Focal length/{focal=$2}
 /Exposure time/{exposure=$2}
 /ISO/{iso=$2}
 /Metering/{metering=$2}
 /^Aperture/{aperture=$2}
 /White/{wb=$2}
 END{
   printf (
      "%s;%s;%s;%s;%s;%s;%s",
      model,focal,exposure,iso,metering,aperture,wb
   );
 }'
  | sed -e"s/\s\s*/ /g"
  | sed -e "s/^\s//g"
  | sed -e "s/;\s/;/g" > $DIR/exif/$output

IFS=";"
read model focal exposure iso metering aperture wb <<END
   $(cat $DIR/exif/$output)
END
multiplier=1
if [ $model == "Canon PowerShot S3 IS" ]; then
  multiplier=6
fi
focal_value=$(echo $focal | awk '{print $1}')
focal_equiv=$(echo "$focal_value * $multiplier" | bc -l)
echo "Shot with $model at $focal ($focal_equiv mm), $exposure, $iso, $metering, $aperture, $wb" > $DIR/exif/$output

 done

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