Something

#!/bin/bash

if [ -z $1 ]; then
	BITRATE=192
else
	BITRATE=$1
fi

if ! mkdir ../MP3; then
	echo "Can't mkdir ../MP3, exiting..."
	exit 1
fi

for a in *
do
       OUTF=`echo "$a" | sed s/\.flac/.mp3/g`

       ARTIST=`metaflac "$a" --show-tag=ARTIST | sed s/.*=//g`
       TITLE=`metaflac "$a" --show-tag=TITLE | sed s/.*=//g`
       ALBUM=`metaflac "$a" --show-tag=ALBUM | sed s/.*=//g`
       GENRE=`metaflac "$a" --show-tag=GENRE | sed s/.*=//g`
       TRACKNUMBER=`metaflac "$a" --show-tag=TRACKNUMBER | sed s/.*=//g`

       flac -c -d "$a" | lame -m j -b $BITRATE -s 44.1 - ../MP3/"$OUTF"
       id3tag -s "$TITLE" -t "$TRACKNUMBER" -a "$ARTIST" -A "$ALBUM" -g "$GENRE" ../MP3/"$OUTF"

done