--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/watcher.go	Wed Oct 14 21:30:04 2020 +0900
@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"time"
+)
+
+func main() {
+	fi, err := os.Lstat(".")
+	if err != nil {
+		log.Fatal(err)
+	}
+	last_mod := fi.ModTime()
+
+	for ; ; {
+		fi, err := os.Lstat("q8.pl")
+		if err != nil {
+			log.Fatal(err)
+		}
+		if last_mod != fi.ModTime() {
+			fmt.Println(">> file updated.")
+			cmd := exec.Command("perl", "q8.pl")
+			out, err := cmd.Output()
+			if err != nil {
+				log.Fatal(err)
+			}
+			fmt.Printf("%s\n", out)
+			last_mod = fi.ModTime()
+		}
+		time.Sleep(2000 * time.Millisecond)
+	}
+}
+