An old script I found lying around to convert FLAC files to MP3

flac2mp3.sh

#!/bin/bash

lame_opts=" --vbr-new -V 2 -B 256 "

for x in "${@}"
do
    FLAC=${x}
    MP3="${FLAC%.flac}.mp3"

    [ -r "$FLAC" ] || { echo can not read file \"$FLAC\" >&1 ; exit 1 ; } ;

    metaflac --export-tags-to=- "$FLAC" | sed 's/=\(.*\)/="\1"/' > tmp.tmp

    . ./tmp.tmp
    rm tmp.tmp

    echo "Converting ${FLAC} to MP3 format"

    flac -c -d "$FLAC" | lame ${lame_opts} \
	--tt "$TITLE" \
	--tn "$TRACKNUMBER" \
	--tg "$GENRE" \
	--ty "$DATE" \
	--tc "$COMMENT" \
	--ta "$ARTIST" \
	--tl "$ALBUM" \
	--add-id3v2 \
	- "$MP3"
done

It is a shell script. Just download and run it from a terminal like so "bash flac2mp3.sh file.flac". You will need to install flac and the lame encoder installed.