wait for printer

reHDDPrinter.py

@@ -9,6 +9,7 @@
 import sysv_ipc 
 import pycstruct
 import os
+import time
 from brother_ql.brother_ql_create import create_label
 from brother_ql.raster import BrotherQLRaster
 import layouter
@@ -17,6 +18,7 @@ str_buffer_size = 64        #keep this synchronous to reHDD
 msg_queue_key = 0x1B11193C0 #keep this synchronous to reHDD
 
 file_name = "output.png"
+printer_path = "/dev/usb/lp0"
 
 def get_struct_format():
     #keep this synchronous to struct in reHDD
@@ -57,10 +59,15 @@ def main():
             shred_timestamp=int(driveData['driveShredTimestamp']),\
             shred_duration=int(driveData['driveShredDuration']))
 
+            while(not os.path.exists(printer_path)):
+                print("Printer not found, waiting ...")
+                time.sleep(30) #sleep 30
+
             layouter.generate_image(drive, rehdd_info, file_name)
             qlr = BrotherQLRaster("QL-570")
             create_label(qlr, file_name, '62')
-            with open("/dev/usb/lp0", 'wb') as file:
+
+            with open(printer_path, 'wb') as file:
                 file.write(qlr.data)
             os.remove(file_name)
     except sysv_ipc.ExistentialError: