Difficulty executing Python on boot - python

I am trying to get this python file with an infinite loop on my raspberry pi to start on boot and stay running while the pi has power. I've tried editing my "etc/rc.local" file and adding the different command variations below. I am certainly referencing the right file and path. I also added a 10 second delay at the beginning of the scrip to make sure everything is in order before it runs. If anyone has any input that'd be great, this is seemingly a common task and I dont know why I am having difficulty.
Additionally I dont have a shebang line at the top of my python script. I dont know if that has anything to do with my problem even though i am specifying the file is a python file.
/usr/bin/python3 /home/pi/Desktop/webplants/mqtt.py &
sudo /usr/bin/python3 /home/pi/Desktop/webplants/mqtt.py &
sudo python3 /home/pi/Desktop/webplants/mqtt.py &
python3 /home/pi/Desktop/webplants/mqtt.py &

You should use systemd. This utility will easily allow you to run a python script on startup. This tutorial should cover it: https://www.dexterindustries.com/howto/run-a-program-on-your-raspberry-pi-at-startup/#systemd

Related

How to run a Python script from Apache on Raspberry Pi?

So, on a Raspberry Pi I'm using a camera app with a web interface, I wanted to add LED lighting by adding a neopixel. I have successfully done this and can now turn it on and off running two python scripts.
Explanation and question:
I have a python script in /usr/local/bin that is executable.
It is owned by 'root root'.
I have a shell script in /var/www/html/macros that is executable and has to run the python script in /usr/local/bin.
The shell script is owned by 'www-data'
When I manually run the python file, it executes the script.
When I manually run the shell script, it executes the python script.
When I run the shell script by clicking on a button on my webpage, it seems to execute the shell script correctly, however, it looks like it doesn't execute the python script.
What can I do to fix this?
I'm not that experienced with permissions, but I wanted to emphasize on the fact that this is a closed system that does not contain any sensitive information. So safety/best practice is not a concern. I just want to make this work.
I'm not an expert in this area, but I believe to access /usr/local/bin/ you need root privileges which explains why you're having success but not Apache.
Rather than give Apache root permissions, it's best to simply remove the requirement from the individual file you want to execute. This can be accomplished by
$ cd /usr/local/bin
$ sudo chmod 777 your_script.py
Now, after 11 hours and a group of people thinking along we found a solution to the problem.
The problem turned out to be that the Web interface can only execute as 'www-data', and the NeoPixel library that the python script depends on needs to be executed as sudo/root.
These two factors make it so that there will never be a direct way of getting the scripts to work together.
However, the idea emerged to use some sort of pipe.
A brilliant user suggested to me to use sshpass. This would allow to pass data to ssh and have it essentially be executed as a root user.
The data from the web interface would be relayed to the sshpass and this would successfully run the needed scripts with the needed privileges.
Special thanks to Minty Trebor and Falcounet from the RRF for LPC/STM Discord!

Crontab executes python script but something is wrong

I am new to programming. I think I'm close to solving my issue, but it finally broke my brain and I need help.
I am running a pygame script as a scheduled task in crontabs. I have one code that executes successfully and does what it should. I have another code that executes, but when it does the screen goes blank, usually displaying some lines that I usually see when the Linux boots up, and it just stays stuck there.
I have gone through both codes and absolutely everything is similar and correct. I have #!/usr/bin/env python at the start of each script.
(Elsewhere it was recommended that I give the exact version, because I use dictionaries in my script and apparently crontab could get confused with the dictionary stuff that pygame uses. I don't fully understand, I tried it but it didn't work on my raspberry pi so I don't think that's the solution.)
Each script runs fine in the terminal.
I have set the PATH variable to the one that the python script uses and also set the SHELL to /bin/bash. In the task I also have "export DISPLAY=:0" (e.g. 12 21 * * * export DISPLAY=:0 && ...). I have found this was the magic trick that got the other code to work. Which made me wonder if there is another environment variable that I need to set in the task?
The difference between the first code and the second code: The second code uses pygame.mixer and plays sound files. In the script, the sound files are in dictionaries (e.g. sound = {"word" : "/absolute/path/to/file.wav", "word2" : ...etc} As I said this code runs fine in terminal.
So why does the one script work and not the other. Both use pygame. The other just uses sound, dictionaries instead of strings, and pygame.mixer as well. My reasoning is that there is an issue with crontab getting stuck on one of these things.
I fixed it. I was running it out of root. When I ran the crontab in the user it worked. It must be because the root couldn't get at the files.
Important tips is to add 'import os' and at some point in the script add 'print(os.environ)' to check all the environment variables when it runs in terminal.
Then copy the $PATH variables to the top of the crontab jobs.
Same with $SHELL.
The $DISPLAY variables need to be put in the line, so for example '* * * * * export DISPLAY=:0 && /usr/bin/python /home/user/file.py'
See how I put absolute paths for both the command and the path to file. I also set absolute paths to files in the script, even if the files are in the same folder as the script. I'm not sure if this is necessary I will check that next. I've seen a lot of people struggle with this issue and the advice usually comes down to these things.

Start two shell sudo scripts in two different terminals from python3

I have an embedded system on which I run code live. Every time I want to run code, I start two scripts in two different terminals: "run1.sh" and "run2.sh". I can see the output of those scripts in my terminals (I wish to too).
Now I want to make a python script that starts those two scripts in two different terminals. I want to still see their output. Also I want to insert a password from the python script to the terminals, since the scripts run in sudo mode. I've played a lot with supbrocess and the PIPES but I've never achieved all of the above requirements simultaneously. How can these requirements be met?
I'm using Ubuntu btw (so I have gnome terminal)
Update : I was probably not clear in my question, but this has to be inside a python script. It is not for my convenience, it's part of an integration process. The code of the script will be part of a larger python program, so the whole point of the question is how do I do it in python.
Based on your new information added I've created an small python script which will launch two terminals and their output separately:
Main script:
mortiz#florida:~/Documents/projects/python/split_python_execution$ cat split_pythonstuff.py
#!/usr/bin/python3
import subprocess
subprocess.call(['gnome-terminal', '-x', 'python', '/home/mortiz/Documents/projects/python/split_python_execution/script1.py'])
subprocess.call(['gnome-terminal', '-x', 'python', '/home/mortiz/Documents/projects/python/split_python_execution/script2.py'])
Script 1:
mortiz#florida:~/Documents/projects/python/split_python_execution$ cat script1.py
#!/usr/bin/python3
while True :
print ('script 1')
Script 2:
mortiz#florida:~/Documents/projects/python/split_python_execution$ cat script2.py
#!/usr/bin/python3
while True:
print ('script 2')
From here I guess you can develop anything you want.
UPDATE: About sudo
Sudoers is a great way of controlling which things can be executed by specific users providing passwords or not.
If you add this line in /etc/sudoers there's not need for a password when you pass sudo to your command:
<YOUR_USER> ALL = NOPASSWD : /usr/bin/python <SCRIPT.py>
In your question as far as I understand you have the password stored inside the script. There's no need to do that and it's a bad practice. Sudoers would be a better way.
Anyway, if you want to do it in an insecure way then refer to this question and place it before the commands in the scripts provided in this answer.
The linked provided works:
echo -e "mypassword\n" | sudo -S python test.py
15
You only need to implement that on the previous code.
You could install Terminator and configure one profile per terminal to run any script you want.
I have a default template which will load 3 terminals and run 3 different commands / or scripts if you wanted to:
When I load that profile the first one will move me to my projects dir and list them. The next one will run df -h to see the space available and the lower my ip configuration.
This way would save you lots of programming and it's quite easy.
UPDATE: It will run any command, bash, zsh, python, etc.. available for your terminal. If the script is locally in your machine:
python <your_script_1> # first terminal profile
python <your_script_2> # second terminal profile
both would be executed "at the same time".
If your scripts are remote in the target machine, simply create a bash script using ssh to connect to the remote machine with a private key and then running the script, the result is the same in both scenarios.
EDIT: The best thing is setting colors and transparency for each terminal, so you can enjoy the penguin's selfie while you work.

Rundeck :: Execute a python script

I am new to Rundeck, so I apologize if I ask a question that probably has an obvious answer I'm overlooking.
I've installed Rundeck on my Windows PC. I've got a couple of Python scripts that I want to execute via Rundeck.
The scripts run fine when I execute them manually.
I created a job in Rundeck, created a single step (script file option) to test the python script.
The job failed after six seconds. When I checked the log, it was because it was executing it line by line rather than letting python run it as an entire script.
How do I fix this?
You had to put:
#!/usr/bin/python
or similar, with location to your python binary, as 1st line. To indicate which interpreter to use for whole file.
okay, so I changed the step type to a command rather than script file and it worked.
I guess my understanding of what a script file is was off.

Unable to run .py file from putty, Syntax error: word unexpected (expecting ")")

I am new to both Python and Linux and as such request simple explanations with minimal assumed knowledge where possible please, however I am more than willing to invest time and effort to learn.
I have a Raspberry Pi 2 (Model B V1.1) that is running Linux. I interact with this pi via putty.
I am trying to create a simple competitive reflex game, consisting of 2 buttons and a single LED. My goal is to have the LED light up after a short interval, and the first player to press their button wins.
I am writing the script for this with python (specifically 2.7.3)
My issue is that i am unable to run ANY .py file from within putty, i always receive the same error:
Syntax error: word unexpected (expecting ")")
To determine if the issue was an error in my code, i created a very very simple .py file, to check if the same error occurs, and it did. So i currently believe even if my code was functional, something is stopping me from running ANY .py file.
The process I am using is as follows:
First I create a new python file from within putty:
sudo nano test.py
Next I enter my python code (very simple for now, as i cannot get ANY .py file to run)
for each in range(5):
print 'hello'
I then press CTRL + O to write the file, hit enter, then CTRL + X to exit
Finally, I make the file executable using
sudo chmod u+x test.py
and try to run it
sudo ./test.py
again, a similar error occurs
Syntax error: "(" unexpected
I then decided to enter the code directly into the python shell, using
sudo python
>>>for each in range(5):
... print 'hello'
This time the output is the desired outcome:
hello
hello
hello
hello
hello
So there is no problem in executing python code directly from the shell, I am just unable to execute any previously saved .py file
Any insight into what could be causing this is much appreciated, and I apologise if I have not provided enough information to be useful for you.
Thanks in advance!
Short answer: Either run these as python filename.py, or else add the line #!/usr/bin/python to the top of your Python scripts.
Long answer: When you run a file from the command line in Linux (which is what the Raspberry Pi is running), by default it assumes that the file is a shell script file (usually Bash script). So it uses the Bash shell (or some other shell, but it's usually Bash) to interpret the file, and Bash doesn't know Python syntax. If you want to run your file using a different interpreter (Python, in this case), you have to add a "magic line" at the top of the file starting with #! (usually pronounced "hash-bang", and sometimes pronounced "shebang" for short). Following the #! characters is the full path of the interpreter to use, e.g. /usr/bin/python for Python scripts. (You can also use /usr/bin/env python as another answer suggested; I prefer /usr/bin/python because it's impossible to get the wrong Python interpreter that way. But that's getting into advanced topics that may be more than you need right now.)
So when you put the line #!/usr/bin/python at the top of your Python scripts, you're telling the Linux system which interpreter to run the program with, and then it should All Just Work™.
Also, STOP using sudo to edit and run these! That's just asking for trouble.
If you wish to execute like this you need the following line as the first line
#!/usr/bin/env python
This will tell bash (or equivalent) to execute the file with the Python interpreter.
If you don't want to do that then you can execute the script like this:
$ python test.py
If you go this route then you don't need to grant execute permissions on the script itself.
Also, scripts shouldn't be executed with sudo unless absolutely necessary.

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