Develop Reference

Reading string arguments passed from batch file to python script

I have seen multiple posts on passing the string but not able to find good solution on reading the string passed to python script from batch file. Here is my problem.
I am calling python script from batch file and passing the argument.
string_var = "123_Asdf"
bat 'testscript.py %string_var%'
I have following in my python code.
import sys
passed_var = sys.argv[1]
When I run the above code I always see below error.
passed_var = sys.argv[1]
IndexError: list index out of range
Has anyone seen this issue before? I am only passing string and expect it to be read as part of the first argument I am passing to the script.

Try this:
import sys
for x,parameter in enumerate(sys.argv):
print(x, parameter)

If I have read your question and its formatting correctly, I think your .bat file should read:
Set string_var="123_Asdf"
"D:\BuildTools\tools\python27\python.exe" testscript.py %string_var%
Or better still:
Set "string_var=123_Asdf"
"D:\BuildTools\tools\python27\python.exe" testscript.py "%string_var%"
Where %string_var% can be passed with or without its enclosing doublequotes.

Your batch file should be a bit simpler, make sure you have your PATH set correctly or else this won't work.
python testscript.py [argument]

Pass the result of Python script to VB.net

I have a python file:
myFile.py
def get_value(data):#pass in data as input parameter
output = process(data)#function to process data
return output
Here, output can be a float number or a string.
I want to call this python script from VB.NET. I searched the web and someone suggested
import System.Diagnostics
Process.Start("C:\python " & "myFile.py")
I am not sure if it is correct. Furthermore, it does not receive output in the python file.
What should I do?
Thank you.

If your python script is just like that your function is never called and therefore doesn't return anything.
I don't know what kind of data you plan to return, if it's simple stuff the perhaps just print it with print(get_value(data)) in the end of the file and capture the printed lines with the VB script?

Using writelines and append to create a file not working

I am trying to create a file that just writes the user's name to a file. I have written:
def main():
f=open("name.txt","a")
name=input("name:")
f.writelines(name)
f.close()
main()
I am wondering what I am missing in order for this to work because it does not save into a text file. Additionally I am using append so I can run this program more than once and continuously add names to it.

The code works fine, but I suspect why it doesn't for you.
In the console, using input function, you need to tell the program that you're sending him a string.
When it asks for the name, you shouldn't input for instance Bernard, but "Bernard".
You should use raw_input instead if you want to get rid of the " character.
PS : Have you tried running your program in the console using python command ? You would have seen the error message pop.

input is used to read integers.
Use raw_input instead. A lot of people don't recommend using input.
It is possible a duplicate: link

Passing Python variable to Powershell parameter using Python's Popen

I am calling a Powershell script within a Python script using Python's subprocess Popen. The Powershell script requires two input parameters: -FilePath and -S3Key. It uploads a file to AWS S3 server. If I pass in hard coded strings, the script works.
os.Popen([r'C:\\WINDOWS\\system32\\WindowsPowerShell\\v1.0\\powershell.exe','-ExecutionPolicy','RemoteSigned','./Upload.ps1 -FilePath \"C:\TEMP\test.txt\" -S3Key \"mytrialtest/test.txt\"'])
However, if I try to pass in Python string variable, the Powershell script errors out saying it can not find the file specified by the filename variable.
filename = 'C:\TEMP\test.txt'
uploadkey = 'mytrialtest/test.txt'
os.Popen([r'C:\\WINDOWS\\system32\\WindowsPowerShell\\v1.0\\powershell.exe','-ExecutionPolicy','RemoteSigned','./Upload.ps1 -FilePath \"filename\" -S3Key \"uploadkey\"'])
Any help would be greatly appreciated. Thanks.

I know, it's an old question, so this is for those who find this question via google:
The solution mentioned in comment has some risks (string injection) and might not work if there are special characters involved. Better:
import subprocess
filename = r'C:\TEMP\test.txt'
uploadkey = 'mytrialtest/test.txt'
subprocess.Popen(['powershell',"-ExecutionPolicy","RemoteSig‌​ned","-File", './Upload.ps1', '-FilePath:', filename , '-S3Key:', uploadkey])
Notice the : appended to the parameter names - in most cases it will also work without the :, but if the value starts with a dash, it will fail without the :.

Python code not writing to file unless run in interpreter

I have written a few lines of code in Python to see if I can make it read a text file, make a list out of it where the lines are lists themselves, and then turn everything back into a string and write it as output on a different file. This may sound silly, but the idea is to shuffle the items once they are listed, and I need to make sure I can do the reading and writing correctly first. This is the code:
import csv,StringIO
datalist = open('tmp/lista.txt', 'r')
leyendo = datalist.read()
separando = csv.reader(StringIO.StringIO(leyendo), delimiter = '\t')
macrolist = list(separando)
almosthere = ('\t'.join(i) for i in macrolist)
justonemore = list(almosthere)
arewedoneyet = '\n'.join(justonemore)
with open('tmp/randolista.txt', 'w') as newdoc:
newdoc.write(arewedoneyet)
newdoc.close()
datalist.close()
This seems to work just fine when I run it line by line on the interpreter, but when I save it as a separate Python script and run it (myscript.py) nothing happens. The output file is not even created. After having a look at similar issues raised here, I have introduced the 'with' parameter (before I opened the output file through output = open()), I have tried flushing as well as closing the file... Nothing seems to work. The standalone script does not seem to do much, but the code can't be too wrong if it works on the interpreter, right?
Thanks in advance!
P.S.: I'm new to Python and fairly new to programming, so I apologise if this is due to a shallow understanding of a basic issue.

Where are the input file and where do you want to save the output file. For this kind of scripts i think that it's better use absolute paths
Use:
open('/tmp/lista.txt', 'r')
instead of:
open('tmp/lista.txt', 'r')
I think that the error can be related to this

It may have something to do with where you start your interpreter.
Try use a absolute path /tmp/randolista.txt instead of relative path tmp/randolista.txt to isolate the problem.