I know that I can run a python script from my bash script using the following:
python python_script.py
But what about if I wanted to pass a variable / argument to my python script from my bash script. How can I do that?
Basically bash will work out a filename and then python will upload it, but I need to send the filename from bash to python when I call it.
To execute a python script in a bash script you need to call the same command that you would within a terminal. For instance
> python python_script.py var1 var2
To access these variables within python you will need
import sys
print(sys.argv[0]) # prints python_script.py
print(sys.argv[1]) # prints var1
print(sys.argv[2]) # prints var2
Beside sys.argv, also take a look at the argparse module, which helps define options and arguments for scripts.
The argparse module makes it easy to write user-friendly command-line interfaces.
Use
python python_script.py filename
and in your Python script
import sys
print sys.argv[1]
Embedded option:
Wrap python code in a bash function.
#!/bin/bash
function current_datetime {
python - <<END
import datetime
print datetime.datetime.now()
END
}
# Call it
current_datetime
# Call it and capture the output
DT=$(current_datetime)
echo Current date and time: $DT
Use environment variables, to pass data into to your embedded python script.
#!/bin/bash
function line {
PYTHON_ARG="$1" python - <<END
import os
line_len = int(os.environ['PYTHON_ARG'])
print '-' * line_len
END
}
# Do it one way
line 80
# Do it another way
echo $(line 80)
http://bhfsteve.blogspot.se/2014/07/embedding-python-in-bash-scripts.html
use in the script:
echo $(python python_script.py arg1 arg2) > /dev/null
or
python python_script.py "string arg" > /dev/null
The script will be executed without output.
I have a bash script that calls a small python routine to display a message window. As I need to use killall to stop the python script I can't use the above method as it would then mean running killall python which could take out other python programmes so I use
pythonprog.py "$argument" & # The & returns control straight to the bash script so must be outside the backticks. The preview of this message is showing it without "`" either side of the command for some reason.
As long as the python script will run from the cli by name rather than python pythonprog.py this works within the script. If you need more than one argument just use a space between each one within the quotes.
and take a look at the getopt module.
It works quite good for me!
Print all args without the filename:
for i in range(1, len(sys.argv)):
print(sys.argv[i])
I was using python project pick to select an option from a list. Below code returns the option and index.
option, index = pick(options, title)
Pick uses curses library from python. I want to pass the output of my python script to shell script.
variable output = $(pythonfile.py)
but it gets stuck on the curses screen. It cannot draw anything. What can be the reason for this?
pick gets stuck because when you use $(pythonfile.py), the shell redirects the output of pythonfile.py as if it were a pipe. Also, the output of pick contains characters for updating the screen (not what you want). You can work around those problems by
redirecting the output of pythonfile.py to /dev/tty
ensuring that your pythonfile.py writes its result to the standard error, and
directing the standard error in the shell script to the output of the $(...) construct.
For example:
#!/bin/bash
foo=$(python basic.py 2>&1 >/dev/tty )
echo "result '$foo'"
and in pythonfile.py, doing
import sys
print(option, index, file=sys.stderr)
rather than
print(option, index)
To pass the output of a Python script to a Bash variable you need to specify the command with which to open the python file inside the variable's declaration.
Like so:
variable_output=$(python pythonfile.py)
Furthermore, if you'd like to pass a variable from Python to bash you could use Python's sys module and then redirect the stderr.
Like so:
test.py
import sys
test_var = (str(3 + 3))
sys.exit(test_var)
test.sh
test_var=$(python3 test.py 2>&1)
echo $testvar
Now, if we run test.sh we get the output 6.
I would like to know if it's possible in a bash script to include a python script in order to write (in the bash script) the return value of a funnction I wrote in my python program ?
For example:
my file "file.py" has a function which returns a variable value "my_value" (which represents the name of a file but anyway)
I want to create a bash script which has to be able to execute a commande line like "ingest my_value"
So do you know how to include a python file in a bash script (import ...?) and how is it possible to call a value from a python file inside a bash script ?
Thank you in advance.
Update
Actually, my python file looks like that:
class formEvents():
def __init__(self):
...
def myFunc1(self): # function which returns the name of a file that the user choose in his computeur
...
return name_file
def myFunc2(self): # function which calls an existing bash script (bash_file.sh) in writing the name_file inside it (in the middle of a line)
subprocess.call(['./bash_file.sh'])
if__name__="__main__":
FE=formEvents()
I don't know if it's clear enough but here is my problem: it's to be able to write name_file inside the bash_file.sh
Jordane
The easiest way of doing this is via the standard UNIX Pipeline and your Shell.
Here's an example:
foo.sh:
#!/bin/bash
my_value=$(python file.py)
echo $my_value
file.py:
#!/usr/bin/env python
def my_function():
return "my_value"
if __name__ == "__main__":
print(my_function())
The way this works is simple:
You launch foo.sh
Bash spawns a subprocess and runs python file.py
Python (and the interpretation of file.py) run the function my_function and print it's return value to "Standard Output"
Bash captures the "Standard Output" of the Python process in my_value
Bash then simply echoes the value stored in my_value also to "Standard Output" and you should see "my_value" printed to the Shell/Terminal.
If the python script outputs the return value to the console, you should be able to just do this
my_value=$(command)
Edit: Damn, beat me to it
Alternatively, you can make the bash script process arguments.
#!/usr/bin/bash
if [[ -n "$1" ]]; then
name_file="$1"
else
echo "No filename specified" >&2
exit 1
fi
# And use $name_file in your script
In Python, your subprocess call should be changed accordingly:
subprocess.call(['./bash_file.sh', name_file])
Is there any easy way to use an applescript like:
set theText to text returned of (display dialog "Please insert Text here:" default answer "" with title "exchange to python" with icon 1)
And use the "theText" variable in python?
You can also run a python script with command line input from AppleScript:
--make sure to escape properly if needed
set pythonvar to "whatever"
set outputvar to (do shell script "python '/path/to/script' '" & pythonvar & "'")
Ned's example has python calling AppleScript, then returning control to python, this is the other way around. Then in Python access list of parameters:
import sys
var_from_as = sys.argv[1] # for 1rst parameter cause argv[0] is file name
print 'this gets returned to AppleScript' # this gets set to outputvar
There are a number of ways to do it. Probably the simplest way, since it does not rely on any third-party Python modules, is to run the script in a child process using the OS X osascript command line utility. By default, osascript returns any output from the AppleScript execution to stdout which can be then be read in Python. You can try it out in the Python interactive interpreter.
With Python 3.4.1:
>>> import subprocess
>>> theText = subprocess.check_output(['osascript', '-e', \
r'''set theText to text returned of (display dialog "Please insert Text here:" default answer "" with title "exchange to python" with icon 1)'''])
>>> theText
b'Hell\xc3\xb6 W\xc3\xb2rld!\n'
>>> print(theText.decode('UTF-8'))
Hellö Wòrld!
With Python 2.7.7:
>>> theText
'Hell\xc3\xb6 W\xc3\xb2rld!\n'
>>> print(theText.decode('UTF-8'))
Hellö Wòrld!
For a real world application, you'll probably want to do some error checking and/or exception catching.
Background
I would like my Python script to pause before exiting using something similar to:
raw_input("Press enter to close.")
but only if it is NOT run via command line. Command line programs shouldn't behave this way.
Question
Is there a way to determine if my Python script was invoked from the command line:
$ python myscript.py
verses double-clicking myscript.py to open it with the default interpreter in the OS?
If you're running it without a terminal, as when you click on "Run" in Nautilus, you can just check if it's attached to a tty:
import sys
if sys.stdin and sys.stdin.isatty():
# running interactively
print("running interactively")
else:
with open('output','w') as f:
f.write("running in the background!\n")
But, as ThomasK points out, you seem to be referring to running it in a terminal that closes just after the program finishes. I think there's no way to do what you want without a workaround; the program is running in a regular shell and attached to a terminal. The decision of exiting immediately is done just after it finishes with information it doesn't have readily available (the parameters passed to the executing shell or terminal).
You could go about examining the parent process information and detecting differences between the two kinds of invocations, but it's probably not worth it in most cases. Have you considered adding a command line parameter to your script (think --interactive)?
What I wanted was answered here: Determine if the program is called from a script in Python
You can just determine between "python" and "bash". This was already answered I think, but you can keep it short as well.
#!/usr/bin/python
# -*- coding: utf-8 -*-
import psutil
import os
ppid = os.getppid() # Get parent process id
print(psutil.Process(ppid).name())
I don't think there's any reliable way to detect this (especially in a cross-platform manner). For example on OS X, when you double-click a .py file and it tuns with "Python Launcher", it runs in a terminal, identically to if you execute it manually.
Although it may have other issues, you could package the script up with something like py2exe or Platypus, then you can have the double-clickable icon run a specific bit of code to differentiate (import mycode; mycode.main(gui = True) for example)
If you run python IDLE then "pythonw.exe" is being used to run coding while when you run the command line "python.exe" is used to run coding. The python folder path can vary so you have to revert the path to the python folder. m = '\\' and m = m[0] is to get m to be '\' because of escaping.
import sys
a = sys.executable
m = '\\'
m = m[0]
while True:
b = len(a)
c = a[(b - 1)]
if c == m:
break
a = a[:(b - 1)]
if sys.executable == a + 'pythonw.exe':
print('Running in Python IDLE')
else:
print('Running in Command line')
Update for later versions (e.g. Python 3.6 on Ubuntu 16.04): The statement to get the name has changed to psutil.Process(os.getpid()).parent().name()
I believe this CAN be done. At least, here is how I got it working in Python 2.7 under Ubuntu 14.04:
#!/usr/bin/env python
import os, psutil
# do stuff here
if psutil.Process(os.getpid()).parent.name == 'gnome-terminal':
raw_input("Press enter to close...")
Note that -- in Ubuntu 14 with the Gnome desktop (aka Nautilus) -- you might need to do this:
from a Nautilus window (the file browser), select Edit(menu)->Preferences(item) then Behavior(tab)->Executable Text Files(section)->Ask Each Time(radio).
chmod your script to be executable, or -- from a Nautilus window (the file browser) -- right click on the file->Properties(item) then Permissions(tab)->Execute:Allow executing file as program(checkbox)
double-click your file. If you select "Run in Terminal", you should see the "Type enter to close..." prompt.
now try from a bash prompt; you should NOT see the prompt.
To see how this works, you can fiddle with this (based on the answer by from #EduardoIvanec):
#!/usr/bin/env python
import os
import sys
import psutil
def parent_list(proc=None, indent=0):
if not proc:
proc = psutil.Process(os.getpid())
pid = proc.pid
name = proc.name
pad = " " * indent
s = "{0}{1:5d} {2:s}".format(pad, pid, name)
parent = proc.parent
if parent:
s += "\n" + parent_list(parent, indent+1)
return s
def invoked_from_bash_cmdline():
return psutil.Process(os.getpid()).parent.name == "bash"
def invoked_as_run_in_terminal():
return psutil.Process(os.getpid()).parent.name == "gnome-terminal"
def invoked_as_run():
return psutil.Process(os.getpid()).parent.name == "init"
if sys.stdin.isatty():
print "running interactively"
print parent_list()
if invoked_as_run_in_terminal():
raw_input("Type enter to close...")
else:
with open('output','w') as f:
f.write("running in the background!\n")
f.write("parent list:\n")
f.write(parent_list())
From the idea behind this answer, adding for Win10 compatibility (Ripped from Python 2.7 script; modify as needed):
import os, psutil
status = 1
if __name__ =="__main__":
status = MainFunc(args)
args = sys.argv
running_windowed = False
running_from = psutil.Process(os.getpid()).parent().name()
if running_from == 'explorer.exe':
args.append([DEFAULT OR DOUBLE CLICK ARGS HERE])
running_windowed = True
if running_windowed:
print('Completed. Exit status of {}'.format(status))
ready = raw_input('Press Enter To Close')
sys.exit(status)
There is a number of switch like statements you could add to be more universal or handle different defaults.
This is typically done manually/, I don't think there is an automatic way to do it that works for every case.
You should add a --pause argument to your script that does the prompt for a key at the end.
When the script is invoked from a command line by hand, then the user can add --pause if desired, but by default there won't be any wait.
When the script is launched from an icon, the arguments in the icon should include the --pause, so that there is a wait. Unfortunately you will need to either document the use of this option so that the user knows that it needs to be added when creating an icon, or else, provide an icon creation function in your script that works for your target OS.
My solution was to create command line scripts using setuptools. Here are a the relevant parts of myScript.py:
def main(pause_on_error=False):
if run():
print("we're good!")
else:
print("an error occurred!")
if pause_on_error:
raw_input("\nPress Enter to close.")
sys.exit(1)
def run():
pass # run the program here
return False # or True if program runs successfully
if __name__ == '__main__':
main(pause_on_error=True)
And the relevant parts of setup.py:
setup(
entry_points={
'console_scripts': [
'myScript = main:main',
]
},
)
Now if I open myScript.py with the Python interpreter (on Windows), the console window waits for the user to press enter if an error occurs. On the command line, if I run 'myScript', the program will never wait for user input before closing.
Although this isn't a very good solution, it does work (in windows at least).
You could create a batch file with the following contents:
#echo off
for %%x in (%cmdcmdline%) do if /i "%%~x"=="/c" set DOUBLECLICKED=1
start <location of python script>
if defined DOUBLECLICKED pause
If you want to be able to do this with a single file, you could try the following:
#echo off
setlocal EnableDelayedExpansion
set LF=^
:: The 2 empty lines are necessary
for %%x in (%cmdcmdline%) do if /i "%%~x"=="/c" set DOUBLECLICKED=1
echo print("first line of python script") %LF% print("second and so on") > %temp%/pyscript.py
start /wait console_title pyscript.py
del %temp%/pyscript.py
if defined DOUBLECLICKED pause
Batch code from: Pausing a batch file when double-clicked but not when run from a console window?
Multi-line in batch from: DOS: Working with multi-line strings
Okay, the easiest way I found and made was to simply run the program in the command line, even if it was ran in the Python IDLE.
exist = lambda x: os.path.exists(x) ## Doesn't matter
if __name__ == '__main__':
fname = "SomeRandomFileName" ## Random default file name
if exist(fname)==False: ## exist() is a pre-defined lambda function
jot(fname) ## jot() is a function that creates a blank file
os.system('start YourProgram.py') ## << Insert your program name here
os.system('exit'); sys.exit() ## Exits current shell (Either IDLE or CMD)
os.system('color a') ## Makes it look cool! :p
main() ## Runs your code
os.system("del %s" % fname) ## Deletes file name for next time
Add this to the bottom of your script and once ran from either IDLE or Command Prompt, it will create a file, re-run the program in the CMD, and exits the first instance.
Hope that helps! :)
I also had that question and, for me, the best solution is to set an environment variable in my IDE (PyCharm) and check if that variable exists to know if the script is being executed either via the command line or via the IDE.
To set an environment variable in PyCharm check:
How to set environment variables in PyCharm?
Example code (environment variable: RUNNING_PYCHARM = True):
import os
# The script is being executed via the command line
if not("RUNNING_PYCHARM" in os.environ):
raw_input("Press enter to close.")
I hope it works for you.
Based on existing solutions and using sets:
import psutil
def running_interactively():
"""Return True if any of our parent processes is a known shell."""
shells = {"cmd.exe", "bash.exe", "powershell.exe", "WindowsTerminal.exe"}
parent_names = {parent.name() for parent in psutil.Process().parents()}
# print(parent_names)
# print(f"Shell in parents? {shells & parent_names}")
return bool(shells & parent_names)
if not running_interactively():
input("\nPress ENTER to continue.")
This answer is currently specific to Windows, but it can be reconfigured to work with other operating systems in theory. Rather than installing psutil module like most of these answers recommend, you can make use of the subprocess module and the Windows tasklist command to explicitly get the name of the parent process of your Python program.
import os
import subprocess
shells = {"bash.exe", "cmd.exe", "powershell.exe", "WindowsTerminal.exe"}
# These are standard examples, but it can also be used to detect:
# - Nested python.exe processes (IDLE, etc.)
# - IDEs used to develop your program (IPython, Eclipse, PyCharm, etc.)
# - Other operating system dependent shells
s = subprocess.check_output(["tasklist", "/v", "/fo", "csv", "/nh", "/fi", f"PID eq {os.getppid()}"])
# Execute tasklist command to get the verbose info without the header (/nh) of a single process in CSV format (/fo csv)
# Such that its PID is equal to os.getppid()
entry = s.decode("utf-8").strip().strip('"').split('","')
# Decode from bytes to str, remove end whitespace and quotations from CSV format
# And split along the quote delimited commas
# This process may differ and require adjustment when used for an OS other than Windows
condition = entry and entry[0] in shells
# Check first that entry is not an empty sequence, meaning the process has already ended
# If it still exists, check if the first element -- the executable -- exists as an element of the set of executables you're looking for
I hope this is helpful for anyone looking for an answer to this problem while minimizing the number of dependencies you'd need.
This was tested in Python 3.8 and uses an f-string in the subprocess.check_output line of the code, so please be sure to convert the f-string to a compatible syntax if you're working with a version of Python before f-strings were introduced.