Py Script in crontab

Help and Support Raspberry Pi
1

Hi, i have a Script called Switch.py , to
Run it i have to write

sudo ./switch.py

and it Worms great.
But now i want to execute it every minute.

So i created with

crontab -e

a New cronjob

*/1 * * * * sudo python ./switch.py

But this doesnt work.

Any idea how to do. that ?

2

Use fully qualified names, eg /usr/bin/python /home/osmc/switch.py

Also suggest you create the job under root using sudo crontab -e

3

Doesnt work too :frowning:[quote=“dillthedog, post:2, topic:35738, full:true”]
Use fully qualified names, eg /usr/bin/python /home/osmc/switch.py

Also suggest you create the job under root using sudo crontab -e
[/quote]

4

That doesn’t help much. Edit the crontab and send stdout and stderr to a log file.

5

crontab -l after making the changes
Make sure you leave a new empty line after editing

6 
*/1 * * * * /usr/bin/sudo /usr/bin/python3 /home/osmc/switch.py

Just the script Works Fine When i test it.
But not in the cronjob i guess.

Behind the command is an empty line.
I restarted cron, cron status is active. I also rebooted the pi.
But the script isnt Running.

How can i See if the cronjob is running and what is the error message if there is one?

7

Depending on what you are doing, you may not need the sudo part. When testing, are you running the script as osmc?

sudo journalctl -f

may help you find the error.

8

Don’t use sudo, put in root’s crontab instead.

9

So you’ve ignored:

  1. Run it under root without sudo
  2. Send stdout and stderr to a log file

How do you know it isn’t running? Perhaps it’s running and failing.

Add this to your (osmc) crontab

*/1 * * * * logger Cron is running

then run sudo journalctl -f to montor the system log. Ctrl-C to stop.

Edit: Missed this first time through:

/usr/bin/python3

python3? OSMC is still on v2.7.

10

hi, first of all thanks for all your help.

  1. How do it do that ? Switch the user to root, than crontab -e and /usr/bin/python3 /home/osmc/switch.py as cronjob? without sudo ?
  2. I have no idea how to do that.
  3. The script sends a command to 433Mhz modul, and i can see if my lamp is on or off :wink: Also if i just type /usr/bin/sudo /usr/bin/python3 /home/osmc/switch.py in SSH ,it works great
  4. I’m not at home at the moment, but i will add your lines to the cron tab.

Thanks for all your support :slight_smile:

11

so what i did now:

sudo su
crontab -e

content of the crontab

*/1 * * * * /usr/bin/python3 /home/osmc/switch.py
*/1 * * * * logger Cron is running

and this is the output of journalctl

Mar 31 19:38:01 osmc CRON[31378]: (root) CMD (logger 
Cron is running)
Mar 31 19:38:01 osmc CRON[31377]: 
pam_unix(cron:session): session opened for user root by 
(uid=0)
Mar 31 19:38:01 osmc CRON[31379]: (root) CMD 
(/usr/bin/python3 /home/osmc/switch.py)
Mar 31 19:38:01 osmc logger[31380]: Cron is running
Mar 31 19:38:01 osmc CRON[31376]: 
pam_unix(cron:session): session closed for user root
Mar 31 19:38:02 osmc CRON[31377]: (CRON) info (No MTA 
installed, discarding output)
Mar 31 19:38:02 osmc CRON[31377]: 
pam_unix(cron:session): session closed for user root

but the script doesnt execute.

any ideas ?

12

Hi. I’ll just run through the questions listed in post #10 first.

I believe that was covered waaaay back in post #2, though the method you used in post #11 is also ok.

2 Send stdout and stderr to a log file. I’m pretty sure a quick google search would have given you the answer. There are a few ways but the one most often used is to tag this to the end of your command >>/tmp/pylog 2>&1 so the full line will now read

/usr/bin/python3 /home/osmc/switch.py >>/tmp/pylog 2>&1

Two things: the file /tmp/pylog is just an arbitrarily chosen name, and could be anything you choose, and the use of double chevrons >> means that log messages will be appended to the file each time the job runs. (A single chevron overwrites the file each time.)

3 The fact that it works under SSH but not in cron suggest some environmental issue, which I hope will be clearer from the log file.

You’ve proven that cron is working, so I suggest you remove the logger message (if you haven’t done already).

13

thanks for your answer :slight_smile: now i see that the error is from the script, cause the log says:

sh: 1: ./raspberry-remote/send: not found

my script is this:

#!/usr/bin/python3
import os
import sys
import urllib.request
 
datei = "switch.txt"
urllib.request.urlretrieve("http://www.server.de/pi/switch.txt", datei)
with open(datei) as txtfile:
    for line in txtfile:
        vars = line.strip().split("#")
        if vars[0] == "a":       
               if vars[1] == "0":
                  os.system("./raspberry-remote/send 10001 4 0")
               elif vars[1] == "1":
                  os.system("./raspberry-remote/send 10001 4 1")
               else:
                  os.system("./raspberry-remote/send 10001 4 0")
os.remove(datei)

do i just have to write the absolute path ?

/home/osmc/raspberry-remote/send

:slight_smile:

14

Sure do. It’s running as root, so its $HOME is not /home/osmc.

I assume you’re sure it needs to run as root…