Better error handling

connect_recipt.sh

@@ -1,4 +1,5 @@
 #!/bin/bash
+set -e
 
 # Try to find the USB Ethernet interface first
 iface=$(ip -o link | awk -F': ' '/enx|enp.*u/{print $2}' | head -n 1)
@@ -16,14 +17,17 @@ else
 	echo "Using USB Ethernet interface: $iface"
 fi
 
-# Assign IP address (only for USB interface, skip eth0)
-# if [[ $iface != "eth0" ]]; then
-	sudo ip addr add 192.168.192.10/24 dev "$iface" 2>/dev/null
-# fi
-
-# Bring interface up
+# Bring interface up before assigning IP
 sudo ip link set "$iface" up
 
-# Scan port 9100 on the printer IP
-nmap -p 9100 192.168.192.168
+# Assign IP address if not already set
+if ! ip addr show dev "$iface" | grep -q "192.168.192.10"; then
+	sudo ip addr add 192.168.192.10/24 dev "$iface"
+fi
+
+# Scan port 9100 on the printer IP and verify it is open
+if ! nmap -p 9100 --open 192.168.192.168 | grep -q "9100/tcp open"; then
+	echo "Printer port 9100 is not open."
+	exit 1
+fi