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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)

Using cron to launch python script in terminal window after reboot

I am trying to launch a python script automatically after boot. I want to launch it in a terminal window because the program gives important feedback in the terminal.
I've researched many ways to do this including crontab, init.d, rc.local, and /etc/xdg/autostart/myscript.desktop.
When I've tested my script manually, calling rc.local from the terminal works, however none of these work after booting.
I've tried many variations, the latest in crontab:
#reboot sleep 60 && xterm -hold -e sudo python /home/pi/newcode/newcode/boot-test.py
Other variations I tried include (calling my python script from a shell script):
#reboot sleep 60 && /home/pi/bin/mount.sh && sh /home/pi/foo1.sh
and
#reboot sleep 60 && /home/pi/bin/mount.sh && sh /home/pi/foo1.sh
Update:
foo1.desktop (saved at /usr/local/bin/foo1):
[Desktop Entry]
...
Name=foo1
Exec=gksu /usr/local/bin/foo1
Terminal=false
Type=Application
Categories=GTK;System;TerminalEmulator;
foo1 (saved at /etc/xdg/autostart/foo1.desktop):
#!/bin/bash
/usr/bin/x-terminal-emulator --command="/home/pi/newcode/newcode/boot-test.py" --title="My foo1"
python script, very simple for now (saved at /home/pi/newcode/newcode/boot-test.py)
sensortype=raw_input("press enter to continue")

Comment:
1. is named foo1.desktop ?
2. is named foo1.sh ?
3. does foo1.sh need to be made executable?
Yes, must be named *.desktop
If you use *.sh, the entry in *.desktop have to be equal
Exec=gksu /usr/local/bin/foo1.sh
Yes, a Bash script have to made executable.
Question: I've test my script (rc.local) manually
Don't use etc/rc.local, it's executed to early for X11.
My /etc/xdg/autostart example:
Create a foo1.desktop with at least the following content:
[Desktop Entry]
...
Name=foo1
Exec=gksu /usr/local/bin/foo1
Terminal=false
Type=Application
Categories=GTK;System;TerminalEmulator;
Copy foo1.desktop or create link to foo1.desktop in /etc/xdg/autostart.
Create /usr/local/bin/foo1 with the following content:
#!/bin/bash
/usr/bin/x-terminal-emulator --command="python path_to_your_*.py" --title="My foo1"
Make /usr/local/bin/foo1, executable.

After trying multiple variation the script that worked contained the following:
#!/bin/bash
/usr/bin/x-terminal-emulator -hold -e sudo python /home/pi/newcode/newcode/hms2-v2.6.py
making the script executable by do the following was also necessary:
sudo chmod 755 /etc/xdg/autostart/foo1.desktop
I never got cron or init.d to work

Raspberry crontab python script at boot

I've been trying to launch a python script at the boot of the Rpi, but everything I've tried until now did not work.
The script is some version of this : https://www.raspberrypi.org/learning/temperature-log/worksheet/ :
#!/usr/bin/python
import os, sys
from subprocess import check_output
from re import findall
from time import sleep, strftime, time
def get_temp():
temp = check_output(["vcgencmd","measure_temp"]).decode("UTF-8")
temp = float(findall("\d+\.\d+",temp)[0])
return(temp)
while True:
log=open("cpu_temp.txt","a")
temp = get_temp()
log.write("{0} {1}".format(strftime("%Y-%m-%d %H:%M:%S"),str(temp))+" degreeC\r\n")
sleep(60)
log.close()
It works fine on its own. I tried editing crontab, with and without the absolute path to Python, as well as editing /etc/rc.local
I know it doesn't work, because it should create a text file and edit it each minute, and it's not created at boot. I have other commands in crontab and rc.local that are working.
Need some help please !

If your script is located at /home/pi/tempcheck.py the you should edit crontab with
sudo crontab -e
and append the line
#reboot python /home/pi/tempcheck.py &
then save and exit.
Further details can be found at http://www.raspberrypi-spy.co.uk/2013/07/running-a-python-script-at-boot-using-cron/
You can check it is running with
ps aux | grep tempcheck.py
Note that if you edit root's crontab, the python process will be run as root. So you should use absolute filenames in the python script:
log=open("/home/pi/cpu_temp.txt","a")

sudo crontab -e
#reboot /usr/bin/python /path/to/file/script.py
/path/to/file/script.py would probably be something like /home/username/script.py
If it still doesn't work you can try giving it execute permission with this:
chmod a+x script.py

You can call your script in the ~/.bashrc file. It will be called at boot or terminal opening.
Just write :
python /path/to/your/script.py
At the end of the .bashrc file.

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