Develop Reference

Why doesn't my cronjob execute as expected?

I edit the crontab in Ubuntu 18.04:
crontab -e
50 21 * * * /data/min/query/sync.sh >> logs/tag.log
Then I saved it and exited. I did this at 21:41pm, and I suppose it will execute it at 21:50pm, but it didn't effect. I checked the logs/tag.log, but nothing occurs.
The content of my sync.sh:
#!/bin/bash
cd /data/min/query
echo 'sync tags now ...'
source venv/bin/activate
python utils/tag_counter.py
echo 'updating resource files are done!!!'
I make the script executable by:
chmod +x sync.sh
So that sync.sh can be executed directly. The script does work when executed at the command line, but not working in the cronjobs. This is the first time I use cronjob. Is there anything I am missing in setting up the cronjob?

one python3 script shoud start a second python3 script

i´ve a few problems with my python3 scripts.
an php script start an python3 script:
$comando = 'python3 /var/www/html/tmp/' . $usersession . '-newtenent-vcenter1.py';
shell_exec("/usr/bin/nohup ".$comando." >/dev/null 2>&1 &");
the python3 script write a few strings to an new created text file.
After all thinks are done, the script sould be start the next python3 script:
os.system('python3 /var/www/html/tmp/' + usersession + '-newtenent-cucm1.py')
BUT, python3 start the script "cucm1.py" and close it imeadlety! The script shoud be open an ssh session with paramiko.
The OS is an Ubuntu 18.x. I´ve added the www-data user to the script directory (so all scripts can be executed by the user www-data):
www-data ALL=(ALL) NOPASSWD: /usr/bin/python3 /var/www/html/
BUT, when we execute the first python3 script from the linux shell (as root) it work´s fine (the second script working fine).
any idea? THANK YOU!

crontab won't run os.system python command

Using ubuntu's 16.04 crontab and #reboot to run python3 script. The script runs properly on reboot as I see the logged output. However, my script's os.system command is not running. It runs fine if ran outside of crontab. My scripts are all executable.
crontab -l output:
SHELL=/bin/bash
#reboot nohup /usr/bin/python3 -u /home/path/scheduler.py >> /path/log.out &
scheduler.py code:
#...(check if web server is running...if not restart)
os.system('nohup /usr/bin/python3 -u /path/webserver/main.py &')
print('this function ran')
When I logged the output of the os.system command , there was no output.
As a side note, I am running python schedule commands to check the general health of a webserver. crontab doesn't seem to be the right tool for this so I just use crontab to start my python scheduler on reboot.
I am using flask as the webserver, and would use gunicorn and systemctrl if I could get it to work... but it didn't so this is my workaround.

The point is that, the command called by os.system is not in default path.
For example, tcpdump is not in /usr/bin/.
So, you can solve the problem by adding the full path of the command.

I was facing the same issue when we try to run python script directly in crontab it just by passes the os.system() commands.
Make launcher.sh:
#!bin/bash
cd /home/pi/
sudo python example.py
Then, make your script executable:
chmod 755 launcher.sh
And at last, add your script to crontab:
crontab -e
and add this line at the end:
#reboot sh /home/pi/launcher.sh
(I set the program to run at each reboot)

Run Python script at startup in Ubuntu

I have a short Python script that needs to run at startup - Ubuntu 13.10. I have tried everything I can think of but can't get it to run. The script:
#!/usr/bin/python
import time
with open("/home/username/Desktop/startup.txt", 'a') as f:
f.write(str(time.time()) + " It worked!")
(The actual script is a bit different, as I'm just using this for testing purposes, but you get the idea.)
I've tried all of the following, with no luck:
Put the command python startuptest.py in crontab, as #reboot
python /home/username/Documents/startuptest.py, both as the regular user and as sudo
Put the command python /home/username/Documents/startuptest.py in /etc/rc.local
Opened Ubuntu's Startup Applications and put the command there
Done all of the preceding, putting the command into a shell script
and calling that shell script instead
Nothing works. I get the feeling I'm missing something simple. Any ideas? (The script runs fine if I just run the command from a terminal.)

Instructions
Copy the python file to /bin:
sudo cp -i /path/to/your_script.py /bin
Add A New Cron Job:
sudo crontab -e
Scroll to the bottom and add the following line (after all the #'s):
#reboot python /bin/your_script.py &
The “&” at the end of the line means the command is run in the background and it won’t stop the system booting up.
Test it:
sudo reboot
Practical example:
Add this file to your Desktop: test_code.py (run it to check that it works for you)
from os.path import expanduser
import datetime
file = open(expanduser("~") + '/Desktop/HERE.txt', 'w')
file.write("It worked!\n" + str(datetime.datetime.now()))
file.close()
Run the following commands:
sudo cp -i ~/Desktop/test_code.py /bin
sudo crontab -e
Add the following line and save it:
#reboot python /bin/test_code.py &
Now reboot your computer and you should find a new file on your Desktop: HERE.txt

Put this in /etc/init (Use /etc/systemd in Ubuntu 15.x)
mystartupscript.conf
start on runlevel [2345]
stop on runlevel [!2345]
exec /path/to/script.py
By placing this conf file there you hook into ubuntu's upstart service that runs services on startup.
manual starting/stopping is done with
sudo service mystartupscript start
and
sudo service mystartupscript stop

If you are on Ubuntu you don't need to write any other code except your Python file's code , Here are the Steps :-
Open Dash (The First Icon In Sidebar).
Then type Startup Applications and open that app.
Here Click the Add Button on the right.
There fill in the details and in the command area browse for your Python File and click Ok.
Test it by Restarting System . Done . Enjoy !!

Create file ~/.config/autostart/MyScript.desktop
with
[Desktop Entry]
Encoding=UTF-8
Name=MyScript
Comment=MyScript
Icon=gnome-info
Exec=python /home/your_path/script.py
Terminal=false
Type=Application
Categories=
X-GNOME-Autostart-enabled=true
X-GNOME-Autostart-Delay=0
It helps me!

In similar situations, I've done well by putting something like the following into /etc/rc.local:
cd /path/to/my/script
./my_script.py &
cd -
echo `date +%Y-%b-%d_%H:%M:%S` > /tmp/ran_rc_local # check that rc.local ran
This has worked on multiple versions of Fedora and on Ubuntu 14.04 LTS, for both python and perl scripts.

nano /etc/rc.local
and edit in
python ~/path-to-script.py
worked for me

Automatically running a python script after boot?

I have written a small python script in Ubuntu 13.10, that when run opens 4 terminals and displays some useful information, is it possible for me to get this to run automatically after I login, I have tried a couple of methods but they all involve it running at start up and this wont leave the terminals displayed.

Bootup:
$ crontab -e
Add:
#boot cd /home/user/; python script.py
Login:
Edit one of these files:
nano /etc/profile.d/myscript.sh
~/.bash_login
And add:
cd /home/user; python script.py
Graphical login:
nano ~/.xinitrc
Add:
eval(cd /home/user; python script.py) &
Ubuntu-Gnome specific login:
nano ~/.gnomerc