use feh to create a slideshow, meant for i3-wm, to be launched at startup

slideshow.sh

#!/bin/bash

#wait (in seconds) for background to change
wait=$((60 * 60))

#in the future, could load files from a general bin/config file
#sed -c -i "s/\($TARGET_KEY *= *\).*/\1$REPLACEMENT_VALUE/" $CONFIG_FILE
dir="$(cat /home/andrew/bin/data/slideshow_all.txt)"
#finds the image files in $dir, optionally can add --max-depth 1 to keep from searching subdirs
files=$(find "$dir" -regex ".*\.\(jpg\|gif\|png\|jpeg\)" | sort -n)

#used to find place of last used background image
latest="$(cat /home/andrew/bin/data/slideshow_latest.txt)"
past_latest=false
tmp=
nl=$'\n'
for line in $files
do
        if $past_latest || [[ $line == $latest  ]] || [ -z "$latest" ]
        then
                tmp+="$line${nl}"
                past_latest=true
        fi
done
tmp=${tmp/%${nl}/}
if [ ! -z "$tmp" ]
then    
        files=$tmp
fi
while true
do
        echo "$files" | while read -r line
        do
                #feh --bg-fill "$line"
                feh --bg-max "$line"
                echo $line > /home/andrew/bin/data/slideshow_latest.txt
                sleep $wait
        done
        files=$(find "$dir" -regex ".*\.\(jpg\|gif\|png\|jpeg\)")
done