#!/bin/sh
#for out; do true; done # get last argument
filelist=$(mktemp ${TMPDIR:-/tmp}/ffconcat.XXXXXX) || exit
pwd="$(pwd)"
for out; do
	[ -e "$pwd/$out" ] \
	&& files="$pwd/$out\n$files" \
	|| ([ -e "$out" ] && files="$out\n$files")
done
echo $files | tail +2 | sed -n "s/\(.\+\)/file '\1'/p"# > $filelist

ffmpeg \
	-f concat \
	-safe 0 \
	-i $filelist \
	-c copy \
	$out