python – Run function from the command line

The Question :

402 people think this question is useful

I have this code:

def hello():
    return 'Hi :)'

How would I run this directly from the command line?

The Question Comments :
  • Probably you meant print "Hi :)" instead of return 'Hi :)'.

The Answer 1

618 people think this answer is useful

With the -c (command) argument (assuming your file is named

$ python -c 'import foo; print foo.hello()'

Alternatively, if you don’t care about namespace pollution:

$ python -c 'from foo import *; print hello()'

And the middle ground:

$ python -c 'from foo import hello; print hello()'

The Answer 2

136 people think this answer is useful

Just put hello() somewhere below the function and it will execute when you do python

For a neater solution you can use this:

if __name__ == '__main__':

That way the function will only be executed if you run the file, not when you import the file.

The Answer 3

72 people think this answer is useful

python -c 'from myfile import hello; hello()' where myfile must be replaced with the basename of your Python script. (E.g., becomes myfile).

However, if hello() is your “permanent” main entry point in your Python script, then the usual way to do this is as follows:

def hello():
    print "Hi :)"

if __name__ == "__main__":

This allows you to execute the script simply by running python or python -m myfile.

Some explanation here: __name__ is a special Python variable that holds the name of the module currently being executed, except when the module is started from the command line, in which case it becomes "__main__".

The Answer 4

38 people think this answer is useful

add this snippet to the bottom of your script

def myfunction():

if __name__ == '__main__':

You can now call your function by running

python myfunction

This works because you are passing the command line argument (a string of the function’s name) into locals, a dictionary with a current local symbol table. The parantheses at the end will make the function be called.

update: if you would like the function to accept a parameter from the command line, you can pass in sys.argv[2] like this:

def myfunction(mystring):
    print mystring

if __name__ == '__main__':

This way, running python myfunction "hello" will output hello.

The Answer 5

29 people think this answer is useful

I wrote a quick little Python script that is callable from a bash command line. It takes the name of the module, class and method you want to call and the parameters you want to pass. I call it PyRun and left off the .py extension and made it executable with chmod +x PyRun so that I can just call it quickly as follow:

./PyRun PyTest.ClassName.Method1 Param1

Save this in a file called PyRun

#!/usr/bin/env python
#make executable in bash chmod +x PyRun

import sys
import inspect
import importlib
import os

if __name__ == "__main__":
    cmd_folder = os.path.realpath(os.path.abspath(os.path.split(inspect.getfile( inspect.currentframe() ))[0]))
    if cmd_folder not in sys.path:
        sys.path.insert(0, cmd_folder)

    # get the second argument from the command line      
    methodname = sys.argv[1]

    # split this into module, class and function name
    modulename, classname, funcname = methodname.split(".")

    # get pointers to the objects based on the string names
    themodule = importlib.import_module(modulename)
    theclass = getattr(themodule, classname)
    thefunc = getattr(theclass, funcname)

    # pass all the parameters from the third until the end of 
    # what the function needs & ignore the rest
    args = inspect.getargspec(thefunc)
    z = len(args[0]) + 2

Here is a sample module to show how it works. This is saved in a file called

class SomeClass:
 def First():
     print "First"

 def Second(x):
    # for x1 in x:
    #     print x1

 def Third(x, y):
     print x
     print y

class OtherClass:
    def Uno():

Try running these examples:

./PyRun PyTest.SomeClass.First
./PyRun PyTest.SomeClass.Second Hello
./PyRun PyTest.SomeClass.Third Hello World
./PyRun PyTest.OtherClass.Uno
./PyRun PyTest.SomeClass.Second "Hello"
./PyRun PyTest.SomeClass.Second \(Hello, World\)

Note the last example of escaping the parentheses to pass in a tuple as the only parameter to the Second method.

If you pass too few parameters for what the method needs you get an error. If you pass too many, it ignores the extras. The module must be in the current working folder, put PyRun can be anywhere in your path.

The Answer 6

9 people think this answer is useful

Let’s make this a little easier on ourselves and just use a module…

Try: pip install compago

Then write:

import compago
app = compago.Application()

def hello():
    print "hi there!"

def goodbye():
    print "see ya later."

if __name__ == "__main__":

Then use like so:

$ python hello
hi there!

$ python goodbye
see ya later.

Note: There’s a bug in Python 3 at the moment, but works great with Python 2.

Edit: An even better option, in my opinion is the module fire by Google which makes it easy to also pass function arguments. It is installed with pip install fire. From their GitHub:

Here’s a simple example.

import fire

class Calculator(object):
  """A simple calculator class."""

  def double(self, number):
    return 2 * number

if __name__ == '__main__':

Then, from the command line, you can run:

python double 10  # 20
python double --number=15  # 30

The Answer 7

6 people think this answer is useful

Interestingly enough, if the goal was to print to the command line console or perform some other minute python operation, you can pipe input into the python interpreter like so:

echo print("hi:)") | python

as well as pipe files..

python <

*Note that the extension does not have to be .py for the second to work. **Also note that for bash you may need to escape the characters

echo print\(\"hi:\)\"\) | python

The Answer 8

5 people think this answer is useful

If you install the runp package with pip install runp its a matter of running:

runp hello

You can find the repository at:

The Answer 9

4 people think this answer is useful

I had a requirement of using various python utilities (range, string, etc.) on the command line and had written the tool pyfunc specifically for that. You can use it to enrich you command line usage experience:

 $ pyfunc -m range -a 1 7 2

 $ pyfunc -m string.upper -a test

 $ pyfunc -m string.replace -a 'analyze what' 'what' 'this'
 analyze this

The Answer 10

1 people think this answer is useful

It is always an option to enter python on the command line with the command python

then import your file so import example_file

then run the command with example_file.hello()

This avoids the weird .pyc copy function that crops up every time you run python -c etc.

Maybe not as convenient as a single-command, but a good quick fix to text a file from the command line, and allows you to use python to call and execute your file.

The Answer 11

1 people think this answer is useful

Something like this:

# Ex to run from terminal
# ip='"hi"'
# python -c "import call_from_terminal as cft; cft.test_term_fun(${ip})"
# or
# fun_name='call_from_terminal'
# python -c "import ${fun_name} as cft; cft.test_term_fun(${ip})"
def test_term_fun(ip):
    print ip

This works in bash.

$ ip='"hi"' ; fun_name='call_from_terminal' 
$ python -c "import ${fun_name} as cft; cft.test_term_fun(${ip})"

The Answer 12

1 people think this answer is useful

Below is the file that has the definition of the function.

def OE(n):
    for a in range(n):
        if a % 2 == 0:
            print(a, "ODD")

Now to call the same from Command prompt below are the options worked for me.

Options 1 Full path of the exe\python.exe -c “import Odd_Even_function; Odd_Even_function.OE(100)”

Option 2 Full path of the exe\python.exe -c “from Odd_Even_function import OE; OE(100)”


The Answer 13

0 people think this answer is useful

This function cannot be run from the command line as it returns a value which will go unhanded. You can remove the return and use print instead

The Answer 14

0 people think this answer is useful

We can write something like this. I have used with python-3.7.x

import sys

def print_fn():

def sum_fn(a, b):
    print(a + b)

if __name__ == "__main__":
    args = sys.argv
    # args[0] = current file
    # args[1] = function name
    # args[2:] = function args : (*unpacked)

python print_fn
python sum_fn 5 8

The Answer 15

-1 people think this answer is useful

Use the python-c tool (pip install python-c) and then simply write:

$ python-c foo 'hello()'

or in case you have no function name clashes in your python files:

$ python-c 'hello()'

The Answer 16

-2 people think this answer is useful

First you have to call the function as they told you or the founction will display nothing in the output, after that save the file and copy the path of the file by right click to the folder of the file and click on”copy file” then go to terminal and write: – cd “the path of the file” – python “name of the file for example (” after that it will display the output of your code.

The Answer 17

-5 people think this answer is useful

Make your life easier, install Spyder. Open your file then run it (click the green arrow). Afterwards your hello() method is defined and known to the IPython Console, so you can call it from the console.

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