iwconfig unavailable to processes started with crontab @reboot?











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this is my first post to stackoverflow, so please bear with me :)



I'm trying to read the output of iwconfig from a python script to determine whether there is a wifi connection. When I run script (via a bash script that first sets the directory) using crontab @reboot (user, not root), subprocess.check_output(['iwconfig']) always throws an [Errno 2]. This is even true when I catch the error using try/except and loop the code, so it is still running when the Wifi is certainly connected (as I can check with running iwconfig manually). When I run the python script from the command line via the same bash script, it works fine. What am I overlooking?



#!/usr/bin/python3

import subprocess
import time
import logging

logging.basicConfig(filename='wifi_check.log', filemode='w', format='%(name)s - %(levelname)s
- %(message)s', level=logging.DEBUG)

logging.info("Checking for Wifi")

for i in range(20):

try:
iwconfig_output = subprocess.check_output(['iwconfig']).decode('utf-8')
except Exception as err:
logging.error(str(i) + str(err))
else:
logging.debug(str(i) + iwconfig_output)
if "ESSID" in iwconfig_output:
logging.info(str(i) + "Wifi active")

time.sleep(10)









share|improve this question


























    up vote
    0
    down vote

    favorite












    this is my first post to stackoverflow, so please bear with me :)



    I'm trying to read the output of iwconfig from a python script to determine whether there is a wifi connection. When I run script (via a bash script that first sets the directory) using crontab @reboot (user, not root), subprocess.check_output(['iwconfig']) always throws an [Errno 2]. This is even true when I catch the error using try/except and loop the code, so it is still running when the Wifi is certainly connected (as I can check with running iwconfig manually). When I run the python script from the command line via the same bash script, it works fine. What am I overlooking?



    #!/usr/bin/python3

    import subprocess
    import time
    import logging

    logging.basicConfig(filename='wifi_check.log', filemode='w', format='%(name)s - %(levelname)s
    - %(message)s', level=logging.DEBUG)

    logging.info("Checking for Wifi")

    for i in range(20):

    try:
    iwconfig_output = subprocess.check_output(['iwconfig']).decode('utf-8')
    except Exception as err:
    logging.error(str(i) + str(err))
    else:
    logging.debug(str(i) + iwconfig_output)
    if "ESSID" in iwconfig_output:
    logging.info(str(i) + "Wifi active")

    time.sleep(10)









    share|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      this is my first post to stackoverflow, so please bear with me :)



      I'm trying to read the output of iwconfig from a python script to determine whether there is a wifi connection. When I run script (via a bash script that first sets the directory) using crontab @reboot (user, not root), subprocess.check_output(['iwconfig']) always throws an [Errno 2]. This is even true when I catch the error using try/except and loop the code, so it is still running when the Wifi is certainly connected (as I can check with running iwconfig manually). When I run the python script from the command line via the same bash script, it works fine. What am I overlooking?



      #!/usr/bin/python3

      import subprocess
      import time
      import logging

      logging.basicConfig(filename='wifi_check.log', filemode='w', format='%(name)s - %(levelname)s
      - %(message)s', level=logging.DEBUG)

      logging.info("Checking for Wifi")

      for i in range(20):

      try:
      iwconfig_output = subprocess.check_output(['iwconfig']).decode('utf-8')
      except Exception as err:
      logging.error(str(i) + str(err))
      else:
      logging.debug(str(i) + iwconfig_output)
      if "ESSID" in iwconfig_output:
      logging.info(str(i) + "Wifi active")

      time.sleep(10)









      share|improve this question













      this is my first post to stackoverflow, so please bear with me :)



      I'm trying to read the output of iwconfig from a python script to determine whether there is a wifi connection. When I run script (via a bash script that first sets the directory) using crontab @reboot (user, not root), subprocess.check_output(['iwconfig']) always throws an [Errno 2]. This is even true when I catch the error using try/except and loop the code, so it is still running when the Wifi is certainly connected (as I can check with running iwconfig manually). When I run the python script from the command line via the same bash script, it works fine. What am I overlooking?



      #!/usr/bin/python3

      import subprocess
      import time
      import logging

      logging.basicConfig(filename='wifi_check.log', filemode='w', format='%(name)s - %(levelname)s
      - %(message)s', level=logging.DEBUG)

      logging.info("Checking for Wifi")

      for i in range(20):

      try:
      iwconfig_output = subprocess.check_output(['iwconfig']).decode('utf-8')
      except Exception as err:
      logging.error(str(i) + str(err))
      else:
      logging.debug(str(i) + iwconfig_output)
      if "ESSID" in iwconfig_output:
      logging.info(str(i) + "Wifi active")

      time.sleep(10)






      python python-3.x cron raspbian iwconfig






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      share|improve this question










      asked Nov 11 at 16:45









      Beat

      32




      32
























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          Errno 2 can indicate that the file is not found.
          Perhaps iwconfig is not in PATH for the user who executes the script. Try using /sbin/iwconfig (the full path) of the executable to rule this out.






          share|improve this answer





















          • thanks a lot, that did it! (i had actually tried the full path but got it wrong).
            – Beat
            Nov 11 at 20:04











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          1 Answer
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          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          0
          down vote



          accepted










          Errno 2 can indicate that the file is not found.
          Perhaps iwconfig is not in PATH for the user who executes the script. Try using /sbin/iwconfig (the full path) of the executable to rule this out.






          share|improve this answer





















          • thanks a lot, that did it! (i had actually tried the full path but got it wrong).
            – Beat
            Nov 11 at 20:04















          up vote
          0
          down vote



          accepted










          Errno 2 can indicate that the file is not found.
          Perhaps iwconfig is not in PATH for the user who executes the script. Try using /sbin/iwconfig (the full path) of the executable to rule this out.






          share|improve this answer





















          • thanks a lot, that did it! (i had actually tried the full path but got it wrong).
            – Beat
            Nov 11 at 20:04













          up vote
          0
          down vote



          accepted







          up vote
          0
          down vote



          accepted






          Errno 2 can indicate that the file is not found.
          Perhaps iwconfig is not in PATH for the user who executes the script. Try using /sbin/iwconfig (the full path) of the executable to rule this out.






          share|improve this answer












          Errno 2 can indicate that the file is not found.
          Perhaps iwconfig is not in PATH for the user who executes the script. Try using /sbin/iwconfig (the full path) of the executable to rule this out.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 11 at 16:52









          Uku Loskit

          29.9k86779




          29.9k86779












          • thanks a lot, that did it! (i had actually tried the full path but got it wrong).
            – Beat
            Nov 11 at 20:04


















          • thanks a lot, that did it! (i had actually tried the full path but got it wrong).
            – Beat
            Nov 11 at 20:04
















          thanks a lot, that did it! (i had actually tried the full path but got it wrong).
          – Beat
          Nov 11 at 20:04




          thanks a lot, that did it! (i had actually tried the full path but got it wrong).
          – Beat
          Nov 11 at 20:04


















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