diff --git a/Interlace/lib/core/input.py b/Interlace/lib/core/input.py
index 57b7327..c88d99f 100644
--- a/Interlace/lib/core/input.py
+++ b/Interlace/lib/core/input.py
@@ -53,13 +53,17 @@ class InputHelper(object):
         for target in targets:
             # replace flags
             print("[DEBUG] ............................................")
+            print("[DEBUG] Commend length: %s" % len(commands))
             for command in commands:
-                command = command.replace("_target_", target)
-                command = command.replace("_output_", arguments.output)
-                command = command.replace("_port_", arguments.port)
-                command = command.replace("_realport_", arguments.realport)
+                command = str(command).replace("_target_", target)
+                if arguments.output:
+                    command = str(command).replace("_output_", arguments.output)
+                if arguments.port:
+                    command = str(command).replace("_port_", arguments.port)
+                if arguments.realport:
+                    command = str(command).replace("_realport_", arguments.realport)
                 final_commands.add(command)
-                print("[DEBUG] Added final command %s" % command)
+                print("[DEBUG] Added final command %s" % str(command))
         return final_commands
 
 
diff --git a/output.txt b/output.txt
new file mode 100644
index 0000000..368aed7
--- /dev/null
+++ b/output.txt
@@ -0,0 +1,20 @@
+PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
+
+PING 10.0.0.4 (10.0.0.4) 56(84) bytes of data.
+
+PING 10.0.0.3 (10.0.0.3) 56(84) bytes of data.
+
+PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
+
+--- 10.0.0.1 ping statistics ---
+70 packets transmitted, 0 received, 100% packet loss, time 728ms
+
+--- 10.0.0.4 ping statistics ---
+70 packets transmitted, 0 received, 100% packet loss, time 728ms
+
+--- 10.0.0.3 ping statistics ---
+70 packets transmitted, 0 received, 100% packet loss, time 728ms
+
+--- 10.0.0.2 ping statistics ---
+70 packets transmitted, 0 received, 100% packet loss, time 728ms
+