Develop Reference

How do I create a cronjob for these commands?

I want to a up a cron job to run a python script each day within a virtual environment. So I've tried to set up a cron job but it does not seem to execute.
If I were to run the program from terminal normally, I would type:
source ig/venv/bin/activat enter to activate my virtual environment
cd ig/mybot/src/ navigate to my directory
python ultimate.py run my program
SO FAR this is my cron job. I've set it to 1 to run every minute just so I can see that it is working but nothing happens.
1 * * * * source ig/venv/bin/activate && cd ig/mybot/src/ && python ultimate.py
Edit: I have updated my program so no command line prompts are required. I am just needing to run these three simple commands.

You can wrap this up with another python script itself. Create a new python script and run it instead of cron.
Have a look into subprocess module.
Example:
Your command would become subprocess.call(['source','ig/venv/bin/activate'])
inside the wrapper python script.
Also, input("Enter the value") will prompt you for user input.
With the above two, your problem will be solved pythonically.

I'm not sure if it's a good idea, but you could do a script like this.
#!/usr/bin/env bash
PYTHON_PROJECT_DIR=/path/to/python/project/dir
pushd ${PYTHON_PROJECT_DIR}
VALUES="first line of stream\nsecondline of stream\n"
pipenv run /path/to/your/script.py < (echo -e $VALUES)
popd
pushd and popd are commands to move with the directory stack, so you'll be in the directory in the top of the stack, so by adding one directory, you move to the working directory, and by poping you'll get back to the initial position.
Using pipenv allows you to run the scripts in the virtual enviroment (It's not that hard to configure), that way you'll use the enviroment variables in the .env files for the project, and you'll only use the dependencies of this project. (python related).
If you pass the values like this, the python script when ever it requests a value from stdin it will use the values that you echoed (line by line, first line is first input and so on)
This could be a way.
Personally when ever I do cronjobs I like to run directly bash scripts, because, I could add extra logging, so having the wrapper script doesn't seem that unreasonable.
Another thing you could do, Is to get the python executable path (for the virtual enviroment), and use that as interpreter, by replacing the #!/usr/bin/env python to #!/path/to/pythons/virtual/env/interpreter
but you won't get the .env variables (may be there is a way to actually get them.

How to make a command that runs Python a script in Windows command line?

Background:
I'm using Windows. I know some of programming with python. I don't know much about batch, which I think I might need to do what I want.
I will show a example so it becomes more clear what I'm trying to do.
Example:
When using git, after you install it, you can call the git command from anywhere of your computer, you can execute git commands, like git init and this will create a git file in your current folder.
I don't know exactly how git works or what language they use but I want to do the same thing, create my own command that I can execute from anywhere in my computer after I "install" my program.
What I'm trying to do:
I want to make my own command and when I call it, it executes a python script.
e.g.
I install my program and it creates a command called myprogram and when I type myprogram in the command line, it's like if I typed python myprogram.py. And myprogram -someargument would be the same as python myprogram.py -someargument.
What I tried until now:
I'm searched for How to make a environment variable that runs Python script? but I never get exactly what I want, is always something like How do I set environment variable using Python script?.
Maybe I'm making the wrong question and the result I want are not showing?
I'm looking for a explanation on how to do this or at least a tutorial/guide.
Edit 1:
As UnholySheep said in the comments, it's not environment variable, its commands, so I changed the question even does what I want to know is the same thing.

Files you need:
First you need a python script (obviously) so I created a file called myprogram.py that have this simple line:
print("This should be from a command")
After you need to make a batch file, in my case I used a .cmd file called myprogram.cmd that have:
#ECHO OFF
python_directory\python.exe python_script_directory\myprogram.py %*
Configurations to make:
You need to set in PATH environment variable the location of the batch file batch_file_directory\myprogram.cmd
And now if you execute in the command line myprogram it will print This should be from a command.
You can also use .exe or .bat files.

Python Script not running in cron

I am trying to run a Python script from cron. I am using crontab to run the command as a user instead of root. My Python script has the shebang at the top #! /usr/bin/env python and I did chmod +x it to make the script executable.
The script does work when running it from a shell but not when using crontab. I did check the /var/log/cron file and saw that the script runs but that absolutely nothing from stdout or stderr prints anywhere.
Finally, I made a small script that prints the date and a string and called that every minute that worked but this other script does not. I am not sure why I am getting these variable results...
Here is my entry in crontab
SHELL=/bin/bash
#min #hour day-of-month month day-of-week command
#-------------------------------------------------------------------------
*/5 * * * * /path/to/script/script.py
Here is the source code of my script that will not run from crontab but will run from the shell it is in when called like so ./script.py. The script is executable after I use the chmod +x command on it, by the way...:
#! /usr/bin/env python
#create a file and write to it
import time
def create_and_write():
with open("py-write-out.out", "a+") as w:
w.write("writing to file. hello from python. :D\n")
w.write("the time is: " + str(time.asctime()) + "\n")
w.write("--------------------------------\n")
def main():
create_and_write()
if __name__ == "__main__":
main()
EDIT
I figured out what was going wrong. I needed to put the absolute file paths in the script otherwise it would write to some directory I had not planned for.

Ok, I guess this thread is still going to help googlers.
I use a workaround to run python scripts with cron jobs. In fact, python scripts need to be handled with delicate care with cron job.
So I let a bash script take care of all of it.I create a bash script which has the command to run the python script. Then I schedule a cron job to run bash script. You can even use a redirector to log the output of bash command executing the python script.For example
#reboot /home/user/auto_delete.sh
auto_delete.sh may contain following lines:-
#!/bin/sh
echo $(date) >> bash_cron_log.txt
/usr/bin/python /home/user/auto_delete.py >> bash_cron_log.txt
So I don' need to worry about Cron Jobs crashing on python scripts.

You can resolve this yourself by following these steps:
Modify the cron as /path/to/script/script.py > /tmp/log 2> &1
Now, let the cron run
Now read the file /tmp/log
You will find out the reason of the issue you are facing, so that you can fix it.
In my experience, the issue is mostly with the environment.
In cron, the env variables are not set. So you may have to explicitly set the env for your script in cron.

I would like to emphasise one more thing. I was trying to run a python script in cron using the same trick (using shell script) and this time it didn't run. It was #reboot cron. So I used redirection in crontab as I mentioned in one of the above comments. And understood the problem.
I was using lot many file handlers in python script and cron runs the script from user's home directory. In that case python could not find the files used for file handlers and will crash.
What I used for troubleshooting was that I created a crontab as below. It would run the start.sh and throw all the stderror or stdoutput to file status.txt and I got error in status.txt saying that the file I used for file handler was not found. That was right because python script was executed by cron from user's home directory and then the script starts searching for files in home directory only.
#reboot /var/www/html/start.sh > /cronStatus/status.txt 2>&1
This will write everything happening during cron execution to status.txt file. You can see the error over there. I will again advice running python scripts using bash scripts for cronjobs. SOLUTION:- Either you use full path for all the files being used in script (which wasn't feasible for me, since I don't want script to be location dependent). Or you execute script from correct directory
So I created my cron as below-
#reboot cd /var/www/html/ && /var/www/html/start.sh
This cron will first change directory to correct location and then start the script. Now I don't have to worry about hardcoding full path for all files in script. Yeah, it may sound being lazy though ;)
And my start.sh looks like-
#!/bin/sh
/usr/bin/python /var/www/html/script.py
Hope it helps
Regards,
Kriss

I had a similar issue but with a little bit different scenario: I had a bash script (run.sh) and a Python script (hello.py). When I typed
sh run.sh
from the script directory, it worked; if I added the sh run.sh command in my crontab, it did not work.
To troubleshoot the issue I added the following line in my run.sh script:
printenv > env.txt
In this way you are able to see the environment variable used when you (or the crontab) run the script. By analyzing the differences between the env.txt generated from the manual run and the crontab run I noticed that the PWD variable was different. In my case I was able to resolve by adding the following line at the top of my .sh script:
cd /PYTHON_SCRIPT_ABSOLUTE_PATH/
Hope this could help you!

Another reason may be that the way we judged executed or not executed is wrong.

How can I start the python shell and automatically initialize it with some commands?

I find that when I start the python shell I have a bunch of commands I always type to get into the state I want. It is tiresome to keep re-typing these commands, so I have bundled them into a script. Now I just type:
execfile('script.py')
as soon as I enter the shell, and it goes through all the steps to get me to the state I need to be in.
Now I'd like to take it one step further. How can I get the python shell to automatically run script.py every time I start the shell, so I don't have to keep re-typing even that one line?

Here's a way without having to mess with environment variables:
For example, if I had a script with the following in it called script.py:
#!/usr/bin/env python
print("example")
I could tell python to run this before bringing me to the interpreter with the -i flag.
$ python -i script.py
example
>>>

I think you're looking for the PYTHONSTARTUP environment variable

I'd suggest you to use IPython, if possible. It gives tones of great features, and autoexec is only one of them. But of course, correct answer is mentioned by #mgilston

Create a file called usercustomize.py, and place it in your USER_SITE directory (which you can find as import site; site._script(). This file will be executed every time you start an interpreter.
There's a similar file called sitecustomize.py which is executed anytime anyone starts Python.

This is a Windows solution, but I'm sure a Unix equivalent could be done. I created a file \MyPythonCode\autoexec.py (the last line of which is a print("Autoexec Complete")) and a BAT file MyPython.Bat which has:
cd \myPythonCode
python -i autoexec.py
I just use the command: mypython
to start the Python environment every time, now.

Shell script change shell in between

I've a shell script with two shebangs, the first one tells #!/bin/sh and after a few lines the other one is #!/usr/bin/env python.
When this script is given executable permission and ran as ./script.sh, the script works fine, uses /bin/sh in first part and uses python interpreter in latter part.
But when the script is run as sh script.sh, the second shebang is not recognized and the script fails. Is there anyway I can force to change the interpreter if the script is run explicitly as sh script.sh.
The reason I need this is because I need to run the scripts through a tool which runs as sh script.sh

As far as I know you cannot have two shebang lines in one script. The shebang works only when -
it is on the first line
it starts in column one
If you need to run python code then have it in another script and then call the script by doing
python path/to/the/script.py

A better way to do this would be to use a shell here document. Something like this:
#!/bin/sh
curdir=`pwd`
/usr/bin/env python <<EOF
import os
print os.listdir("$curdir")
EOF
This way, you won't need to distribute the code on two separate files.
As you see, you can even access shell variables from the python code.

have your script.sh script invoke the python interpreter directly:
#!/bin/sh
# include full path if needed
python (your python interpreter arguments)