simple script to automate merging converted mp3 files into single mp3 and add cover image

merge_mp3.sh

#!/usr/bin/bash
# Keith Kim, 2021-06
# This is to automate merging mp3 files and add cover image for audible audio book files converted to mp3 using AAXtoMP3


OIFS="$IFS"
IFS=$'\n'
for authorpath in `find . -maxdepth 1 -type d -print`
do 
    if [ "." == "$authorpath" ]; then continue; fi
    echo "### ==============================================="
    echo "### Author path: $authorpath"
    pushd $authorpath > /dev/null

    for bookpath in `find . -maxdepth 1 -type d -print`
    do
        if [ "." == "$bookpath" ]; then continue; fi
        echo "### Book path: $bookpath"
        pushd "$bookpath" > /dev/null
        rm mp3list.lst &> /dev/null
        rm merged.mp3 &> /dev/null
        path="`pwd`"
        author="`echo $authorpath | sed "s/\.\///"`"
        book="`echo $bookpath | sed "s/\.\///"`"
        echo "### --------------------"
        echo "### Author: $author"
        echo "### Book: $book"
        echo "### --------------------"

        for mp3file in $(ls *.mp3)
        do
            echo "### $mp3file"
            echo "file '$path/$mp3file'" >> mp3list.lst
        done

        ffmpeg -f concat -safe 0 -i mp3list.lst    \
            -metadata artist="$author"          \
            -metadata title="$book"             \
            -c copy $path/merged.mp3
        mid3v2 -p cover.jpg merged.mp3
        mv merged.mp3 "$author-$book.mp3"
        popd > /dev/null
    done
    popd > /dev/null
done