--- a/bin/basicopt	Tue Jun 20 01:33:06 2017 +0900
+++ b/bin/basicopt	Fri Jul 07 19:35:52 2017 +0900
@@ -1,11 +1,11 @@
 #!/bin/sh
 get_filename() {
-	printf "%s\n" "$*" | sed -e 's/^\(.*\)\.[^.]*$/\1/'
+	printf '%s\n' "$*" | sed -e 's/^\(.*\)\.[^.]*$/\1/'
 }
 get_extension() {
-	if [ -n "$(printf "%s\n" "$*" | sed -e 's/^[^.]*//')" ]; then
-		printf "%s\n" "$*" | sed -e 's/^.*\(\.[^.]*$\)/\1/'
+	if [ -n "$(printf '%s\n' "$*" | sed -e 's/^[^.]*//')" ]; then
+		printf '%s\n' "$*" | sed -e 's/^.*\(\.[^.]*$\)/\1/'
 	else
-		printf "%s\n" ""
+		printf '%s\n' ""
 	fi
 }