fix(utils): now it can be successfully restarted when deployed as systemd service

- Add `getSystemdServiceName` function to get systemd service name.
- When detected as systemd sevice, use `systemctl restart` to restart the program then exit.

utils/sys.go

@@ -0,0 +1,41 @@
+package utils
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"runtime"
+)
+
+func getSystemdServiceName() (string, error) {
+	data, err := os.ReadFile("/proc/self/cgroup")
+	if err == nil {
+		for _, line := range strings.Split(string(data), "\n") {
+			if !strings.Contains(line, ".service") {
+				continue
+			}
+			for _, part := range strings.Split(line, "/") {
+				part = strings.TrimSpace(part)
+				if strings.HasSuffix(part, ".service") {
+					return part, nil
+				}
+			}
+		}
+	}
+	return "", fmt.Errorf("could not determine systemd service name from cgroup")
+}
+
+func getInitSystem() string {
+	if runtime.GOOS == "windows" {
+		return "windows"
+	}
+	if runtime.GOOS == "linux" {
+		if _, err := os.Stat("/run/systemd/system"); err == nil {
+			return "systemd"
+		}
+		if _, err := os.Stat("/etc/init.d"); err == nil {
+			return "init.d"
+		}
+	}
+	return "unknown"
+}