Something

#! /bin/sh# Dialog box to choose thumb's sizeSIZE=`zenity --list --title="Choose the thumbnail's size" --radiolist --column="Check" --column="Size" "" "640x480" "" "800x600" "" "1024x768"`if [ "${SIZE}" == "" ]; then    zenity --error --text="Size not defined by user.Please choose a size to use. "exit 1fi# How many files to make the progress barPROGRESS=0NUMBER_OF_FILES=`find -iname "*.jpg" -maxdepth 1 | wc -l`let "INCREMENT=100/$NUMBER_OF_FILES"mkdir -p resized# Creating thumbnails. Specific work on picture should be add there as convert's option(for i in *.jpg *.JPG; doecho "$PROGRESS";echo "# Resizing $i";convert -resize "${SIZE}"  -bordercolor black -border 10x10 -quality 85  "${i}" resized/"${i}"let "PROGRESS+=$INCREMENT"done) | zenity  --progress --title "$Creating thumbnails..." --percentage=0