run program in Python shell - python

I have a demo file: test.py.
In the Windows Console I can run the file with: C:\>test.py
How can I execute the file in the Python Shell instead?


Use execfile for Python 2:
>>> execfile('C:\\test.py')
Use exec for Python 3
>>> exec(open("C:\\test.py").read())


If you're wanting to run the script and end at a prompt (so you can inspect variables, etc), then use:
python -i test.py
That will run the script and then drop you into a Python interpreter.


It depends on what is in test.py. The following is an appropriate structure:
# suppose this is your 'test.py' file
def main():
"""This function runs the core of your program"""
print("running main")
if __name__ == "__main__":
# if you call this script from the command line (the shell) it will
# run the 'main' function
main()
If you keep this structure, you can run it like this in the command line (assume that $ is your command-line prompt):
$ python test.py
$ # it will print "running main"
If you want to run it from the Python shell, then you simply do the following:
>>> import test
>>> test.main() # this calls the main part of your program
There is no necessity to use the subprocess module if you are already using Python. Instead, try to structure your Python files in such a way that they can be run both from the command line and the Python interpreter.


For newer version of python:
exec(open(filename).read())


If you want to avoid writing all of this everytime, you can define a function :
def run(filename):
exec(open(filename).read())
and then call it
run('filename.py')


From the same folder, you can do:
import test

Related

How to run a python file while one python file is running

I have two files main.py& test.py
Suppose the main file main.py is running and after a point of time I want to run test.py
I cannot use:
import test or os.system("python test.py") because this run python file in same terminal but I want to run the test.py in other terminal
So I mean to say in one terminal main.py is running after a point a new terminal opens and run test.py
Any solutions?
Thanks :D

If I understand correctly you want to run a python script when some condition is fulfilled so I would recommend calling the "test.py" using a subprocess library (bear in mind there are other methods) like this:
import subprocess
if(your_condition):
subprocess.call(['python', 'test.py', testscript_arg1, testscript_val1,...])
as mentioned here: Using a Python subprocess call to invoke a Python script

Export a variable from bash and use it in Python

I am trying to write a script which is executing couple of things on a Linux server and I would like to use bash for most of the Linux specific commands and only use Python for the most complex stuff, but in order to do that I will need to export some variables from the bash script and use them in the python script and I didn't find a way how I can do that. So I have tried to create two very little scripts to test this functionality:
1.sh is a bash script
#!/bin/bash
test_var="Test Variable"
export test_var
echo "1.sh has been executed"
python 2.sh
2.sh is a Python script:
#!/usr/bin/env python3
print("The python script has been invoked successfully")
print(test_var)
As you can guess when I execute the first script the second fails with the error about unknown variable:
$ ./1.sh
1.sh has been executed
The python script has been invoked successfully
Traceback (most recent call last):
File "2.sh", line 4, in <module>
print(test_var)
NameError: name 'test_var' is not defined
The reason why I am trying to do that is because I am more comfortable with bash and I want to use $1, $2 variables in bash. Is this also possible in Python?
[EDIT] - I have just found out how I can use $1 and $2 it in Python. You need to use sys.argv[1] and sys.argv[2] and import the sys module import sys

To use environment variables from your python script you need to call:
import os
os.environ['test_var']
os.environ is a dictionary with all the environment variables, you can use all the method a dict has. For instance, you could write :
os.environ.get('test_var', 'default_value')

Check python extension it should be .py instead of .sh
1.sh
#!/bin/bash
test_var="Test Variable"
export test_var
echo "1.sh has been executed"
python 2.py
os library will gave you the access the environment variable. Following python code will gave you the required result,
#!/usr/bin/env python3
import os
print("The python script has been invoked successfully")
print(os.environ['test_var'])
Check for reference : How do I access environment variables from Python?

How to run module from command line?

Suppose there is a module somewhere, which I can import with
from sound.effects import echo
How can I run echo directly from command line?
Command
python sound/effects/echo.py
does not work since the relative path is generally incorrect

If the module has top-level code executing on import, you can use the -m switch to run it from the command line (using Python attribute notation):
python -m sound.effect.echo
The module is then executed as a script, so a if __name__ == '__main__': guard will pass. See for example the timeit module, which executes the timeit.main() function when run from the command line like this.

How to run a python script from IDLE interactive shell?

How do I run a python script from within the IDLE interactive shell?
The following throws an error:
>>> python helloworld.py
SyntaxError: invalid syntax

Python3:
exec(open('helloworld.py').read())
If your file not in the same dir:
exec(open('./app/filename.py').read())
See https://stackoverflow.com/a/437857/739577 for passing global/local variables.
In deprecated Python versions
Python2
Built-in function: execfile
execfile('helloworld.py')
It normally cannot be called with arguments. But here's a workaround:
import sys
sys.argv = ['helloworld.py', 'arg'] # argv[0] should still be the script name
execfile('helloworld.py')
Deprecated since 2.6: popen
import os
os.popen('python helloworld.py') # Just run the program
os.popen('python helloworld.py').read() # Also gets you the stdout
With arguments:
os.popen('python helloworld.py arg').read()
Advance usage: subprocess
import subprocess
subprocess.call(['python', 'helloworld.py']) # Just run the program
subprocess.check_output(['python', 'helloworld.py']) # Also gets you the stdout
With arguments:
subprocess.call(['python', 'helloworld.py', 'arg'])
Read the docs for details :-)
Tested with this basic helloworld.py:
import sys
if len(sys.argv) > 1:
print(sys.argv[1])

You can use this in python3:
exec(open(filename).read())

The IDLE shell window is not the same as a terminal shell (e.g. running sh or bash). Rather, it is just like being in the Python interactive interpreter (python -i). The easiest way to run a script in IDLE is to use the Open command from the File menu (this may vary a bit depending on which platform you are running) to load your script file into an IDLE editor window and then use the Run -> Run Module command (shortcut F5).

EASIEST WAY
python -i helloworld.py #Python 2
python3 -i helloworld.py #Python 3

Try this
import os
import subprocess
DIR = os.path.join('C:\\', 'Users', 'Sergey', 'Desktop', 'helloword.py')
subprocess.call(['python', DIR])

execFile('helloworld.py') does the job for me. A thing to note is to enter the complete directory name of the .py file if it isnt in the Python folder itself (atleast this is the case on Windows)
For example, execFile('C:/helloworld.py')

In a python console, one can try the following 2 ways.
under the same work directory,
1.
>> import helloworld
# if you have a variable x, you can print it in the IDLE.
>> helloworld.x
# if you have a function func, you can also call it like this.
>> helloworld.func()
2.
>> runfile("./helloworld.py")

For example:
import subprocess
subprocess.call("C:\helloworld.py")
subprocess.call(["python", "-h"])

In Python 3, there is no execFile. One can use exec built-in function, for instance:
import helloworld
exec('helloworld')

In IDLE, the following works :-
import helloworld
I don't know much about why it works, but it does..

To run a python script in a python shell such as Idle or in a Django shell you can do the following using the exec() function. Exec() executes a code object argument. A code object in Python is simply compiled Python code. So you must first compile your script file and then execute it using exec(). From your shell:
>>>file_to_compile = open('/path/to/your/file.py').read()
>>>code_object = compile(file_to_compile, '<string>', 'exec')
>>>exec(code_object)
I'm using Python 3.4. See the compile and exec docs for detailed info.

I tested this and it kinda works out :
exec(open('filename').read()) # Don't forget to put the filename between ' '

you can do it by two ways
import file_name
exec(open('file_name').read())
but make sure that file should be stored where your program is running

On Windows environment, you can execute py file on Python3 shell command line with the following syntax:
exec(open('absolute path to file_name').read())
Below explains how to execute a simple helloworld.py file from python shell command line
File Location: C:/Users/testuser/testfolder/helloworld.py
File Content: print("hello world")
We can execute this file on Python3.7 Shell as below:
>>> import os
>>> abs_path = 'C://Users/testuser/testfolder'
>>> os.chdir(abs_path)
>>> os.getcwd()
'C:\\Users\\testuser\\testfolder'
>>> exec(open("helloworld.py").read())
hello world
>>> exec(open("C:\\Users\\testuser\\testfolder\\helloworld.py").read())
hello world
>>> os.path.abspath("helloworld.py")
'C:\\Users\\testuser\\testfolder\\helloworld.py'
>>> import helloworld
hello world

There is one more alternative (for windows) -
import os
os.system('py "<path of program with extension>"')

Why different behaviors between running Python module as an executable vs. Python [filename]

So, I created a simple python module, test.py
import commands
def main():
cmd = 'ls -l'
(status, output) = commands.getstatusoutput(cmd)
print status, output
if __name__ == '__main__':
main()
When I ran it using "Python test.py", I got the result that I expected. But when I ran it as an executable (yes, it has the 'x' permission), the program didn't respond at all and I had to Ctrl+C to quit it. Why is that? Shouldn't both ways give the same result?

Add a hash-bang line to the top:
#!/usr/bin/env python
import commands
...
This tells your system what interpreter to use to execute the script. Without it it doesn't know if it's a shell script, Perl script, Python script, what.

You need the hashbang to be the first line of your script, referencing the path of the Python interpreter. Otherwise, all the OS knows is that you're trying to execute a script, and it has no idea how to go about doing that.

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