--- a/s4-funcs.sh	Wed Dec 27 17:40:34 2023 +0900
+++ b/s4-funcs.sh	Thu Dec 28 11:27:06 2023 +0900
@@ -476,6 +476,13 @@
 }
 _m4() {
   #S4NAME=f,f,f
+  if m4 --version | grep -q GNU; then
+    if type om4; then		# https://github.com/ibara/m4
+      m4() {
+	om4 "$@"
+      }
+    fi
+  fi >/dev/null 2>&1
   m4 ${S4NAME:+"-D_S4NAME_=${S4NAME}"} ${S4CSS:+-D_S4CSS_="$S4CSS"} \
      ${S4WORLD:+-D_S4WORLD_="$S4WORLD"} \
      ${S4WORLDNAME:+-D_S4WORLDNAME_="$S4WORLDNAME"} \
@@ -485,6 +492,17 @@
 if ! type gdate && date --version | grep -q GNU; then
   gdate() date "$@"
 fi >/dev/null 2>&1
+if ! type md5 && type md5sum && md5sum --version | grep -q GNU; then
+  md5() {
+    if [ -z "$1" ]; then
+      md5sum | cut -d' ' -f 1
+    else
+      for f; do
+	printf "MD5 (%s) = %s\n" "$f" "$(md5 < $f)"
+      done
+    fi
+  }
+fi >/dev/null 2>&1
 ismember() {
   # $1=user, $2=group
 #err ismem: "select user from grp_mem where gname=$(sqlquote $2) and user='$1';"