set -e
-[ "x$1" = "x" -o "x$2" = x ] && { echo "usage: $(basename $0) <source_m3u8_url> <output_file>" 1>&2; exit 1; }
+{ [ "x$1" = "x" ] || [ "x$2" = x ]; } && { echo "usage: $(basename "$0") <source_m3u8_url> <output_file>" 1>&2; exit 1; }
SOURCE_URL="$1"
OUTPUT_FILE="$2"