Create a .tar.xz file from a .rsn file (SNES music file)

rsntotarxz.sh

#!/usr/bin/env bash
# create .tar.xz out of a .rsn file

set -e

if [[ $# -ne 2 ]]; then
    echo "usage: rsntotarxz input.rsn output.tar.xz" >&2
    exit 1
fi

infile="$1"
outfile="$2"
temp_folder="/tmp/rsntotarxz"

if ! [ -x "$(command -v unrar)" ]; then
    echo "error: unrar is not installed" >&2
    exit 1
fi

if ! [ -x "$(command -v tar)" ]; then
    echo "error: tar is not installed" >&2
    exit 1
fi

if ! [ -x "$(command -v xz)" ]; then
    echo "error: xz is not installed" >&2
    exit 1
fi

if [ -d "$temp_folder" ]; then
    echo "error: temporary folder '$temp_folder' already exists, exiting" >&2
    exit 1
fi

if [ -f "$outfile" ]; then
    echo "error: output file '$outfile' already exists, exiting" >&2
    exit 1
fi

mkdir $temp_folder
unrar x $infile $temp_folder
# env GZIP=-9 tar cvzf $outfile -C $temp_folder .
env XZ_OPT=-9e tar cJf $outfile -C $temp_folder .
rm -rf $temp_folder