-# - m4 (.m4): pipe $2.m4 through m4 then write it to $2
-# - awk (.in): pipe $2.in through awk then write it to $2
-# - cat ($3): copy $2$3 to $2
+# - m4 (.m4): pipe $2.m4 through m4 then write it to $2
+# - awk (.in): pipe $2.in through awk then write it to $2
+# - perl (.in): pipe $2.in through perl then write it to $2
+# - cat ($3): copy $2$3 to $2