diff --git a/setup_cups.sh b/setup_cups.sh
index 8102e7f..333c97d 100755
--- a/setup_cups.sh
+++ b/setup_cups.sh
@@ -1180,6 +1180,7 @@ PING_TARGETS="$ping_targets"
 FAIL_THRESHOLD=3
 DHCP_AFTER_FAILURE=1
 LOG_FILE="/var/log/cups-watchdog/network.log"
+MAX_LOG_SIZE_KB=256
 EOF
         chmod 600 "$config_dir/network-watchdog.conf"
     else
@@ -1197,6 +1198,7 @@ COMMAND_TIMEOUT=8
 FAIL_THRESHOLD=2
 RESTART_COOLDOWN=60
 LOG_FILE="/var/log/cups-watchdog/print.log"
+MAX_LOG_SIZE_KB=256
 EOF
         chmod 600 "$config_dir/print-watchdog.conf"
     else
@@ -1531,7 +1533,7 @@ main() {
     success "Avahi 服务已启动并设置开机自启"
 
     # 8. 安装守护脚本
-    install_watchdogs
+    install_watchdogs || warn "守护脚本安装失败，请稍后重新运行安装脚本或手动检查 watchdog 目录"
 
     # 更新IP地址（如果配置了静态IP）
     LOCAL_IP=$(get_ip)
@@ -1577,6 +1579,9 @@ main() {
         echo -e "  ${GREEN}          ${NC} 配置目录: /etc/cups-watchdog/"
         echo -e "  ${GREEN}          ${NC} 日志目录: /var/log/cups-watchdog/"
         echo ""
+    else
+        echo -e "  ${YELLOW}[守护脚本]${NC} 未检测到已启用状态，请检查安装日志"
+        echo ""
     fi
     echo -e "  ${YELLOW}下一步:${NC}"
     echo "  1. 用浏览器打开上面的地址"
diff --git a/watchdog/network-watchdog.sh b/watchdog/network-watchdog.sh
index 9a4e35c..a485192 100644
--- a/watchdog/network-watchdog.sh
+++ b/watchdog/network-watchdog.sh
@@ -24,6 +24,7 @@ PING_TARGETS="223.5.5.5 114.114.114.114"
 FAIL_THRESHOLD=3
 DHCP_AFTER_FAILURE=1
 LOG_FILE="/var/log/cups-watchdog/network.log"
+MAX_LOG_SIZE_KB=256
 
 if [ -f "$CONFIG_FILE" ]; then
     # shellcheck disable=SC1090
@@ -33,9 +34,29 @@ fi
 mkdir -p "$STATE_DIR"
 mkdir -p "$(dirname "$LOG_FILE")" 2>/dev/null || true
 
+acquire_lock() {
+    local lock_dir="$STATE_DIR/network.lock"
+
+    if ! mkdir "$lock_dir" 2>/dev/null; then
+        echo "$(date '+%Y-%m-%d %H:%M:%S') [network-watchdog] another run is active"
+        exit 0
+    fi
+    trap 'rmdir "$lock_dir" 2>/dev/null || true' EXIT
+}
+
+rotate_log() {
+    local max_bytes=$((MAX_LOG_SIZE_KB * 1024))
+
+    if [ -f "$LOG_FILE" ] && [ "$(wc -c < "$LOG_FILE" 2>/dev/null || echo 0)" -gt "$max_bytes" ]; then
+        mv "$LOG_FILE" "$LOG_FILE.1" 2>/dev/null || true
+        : > "$LOG_FILE"
+    fi
+}
+
 log_msg() {
     local msg="$1"
     local line
+    rotate_log
     line="$(date '+%Y-%m-%d %H:%M:%S') [network-watchdog] $msg"
     echo "$line"
     echo "$line" >> "$LOG_FILE" 2>/dev/null || true
@@ -223,8 +244,22 @@ configure_static() {
 }
 
 connectivity_ok() {
+    local iface
+    local gateway
     local target
 
+    iface="$(detect_interface)"
+    if [ -n "$iface" ] && [ -f "/sys/class/net/$iface/carrier" ]; then
+        if [ "$(cat "/sys/class/net/$iface/carrier" 2>/dev/null || echo 0)" != "1" ]; then
+            return 1
+        fi
+    fi
+
+    gateway="$(ip route show default 2>/dev/null | awk '{print $3; exit}')"
+    if [ -n "$gateway" ] && ping -c 1 -W 2 "$gateway" >/dev/null 2>&1; then
+        return 0
+    fi
+
     for target in $PING_TARGETS; do
         [ -n "$target" ] || continue
         if ping -c 1 -W 2 "$target" >/dev/null 2>&1; then
@@ -260,12 +295,15 @@ check_network() {
 
 case "${1:-check}" in
     check)
+        acquire_lock
         check_network
         ;;
     dhcp)
+        acquire_lock
         configure_dhcp
         ;;
     static)
+        acquire_lock
         configure_static
         ;;
     *)
diff --git a/watchdog/print-watchdog.sh b/watchdog/print-watchdog.sh
index 417a65b..f5fb6a7 100644
--- a/watchdog/print-watchdog.sh
+++ b/watchdog/print-watchdog.sh
@@ -18,6 +18,7 @@ COMMAND_TIMEOUT=8
 FAIL_THRESHOLD=2
 RESTART_COOLDOWN=60
 LOG_FILE="/var/log/cups-watchdog/print.log"
+MAX_LOG_SIZE_KB=256
 
 if [ -f "$CONFIG_FILE" ]; then
     # shellcheck disable=SC1090
@@ -27,9 +28,29 @@ fi
 mkdir -p "$STATE_DIR"
 mkdir -p "$(dirname "$LOG_FILE")" 2>/dev/null || true
 
+acquire_lock() {
+    local lock_dir="$STATE_DIR/print.lock"
+
+    if ! mkdir "$lock_dir" 2>/dev/null; then
+        echo "$(date '+%Y-%m-%d %H:%M:%S') [print-watchdog] another run is active"
+        exit 0
+    fi
+    trap 'rmdir "$lock_dir" 2>/dev/null || true' EXIT
+}
+
+rotate_log() {
+    local max_bytes=$((MAX_LOG_SIZE_KB * 1024))
+
+    if [ -f "$LOG_FILE" ] && [ "$(wc -c < "$LOG_FILE" 2>/dev/null || echo 0)" -gt "$max_bytes" ]; then
+        mv "$LOG_FILE" "$LOG_FILE.1" 2>/dev/null || true
+        : > "$LOG_FILE"
+    fi
+}
+
 log_msg() {
     local msg="$1"
     local line
+    rotate_log
     line="$(date '+%Y-%m-%d %H:%M:%S') [print-watchdog] $msg"
     echo "$line"
     echo "$line" >> "$LOG_FILE" 2>/dev/null || true
@@ -150,9 +171,11 @@ check_print_stack() {
 
 case "${1:-check}" in
     check)
+        acquire_lock
         check_print_stack
         ;;
     restart)
+        acquire_lock
         restart_print_stack
         ;;
     *)