How to write powershell output to file? [Python]

Question

I am having this problem where I can print out the powershell code output with the print() function, but when I try to do the same, except this time I write the output to a file, the only thing that is written in the file is "0", why would the printed output be different from when I write the same exact code, except that I this time "print" it to a text file.

I want the text file to contain exactly what the print function prints to the terminal, why isn't it working, and how can I get it to work?? Here are some pictures and the code:

import os
import time
def monitorprocess(process):
    run = True

    time_q = float(input("How many minutes before each check? "))
    while run:
        
        timespan = os.system(f'powershell New-TimeSpan -Start(Get-process {process}).StartTime')
        try:
            open(f'powershellpython\{process}.txt','x')
        except:
            pass
        with open(f'powershellpython\{process}.txt',"w") as file:
            file.write(str(timespan))
        print(timespan)

        time.sleep(time_q*60)

def processes():
    process = input("What is the name of your process, if you are unsure, type 'get-process', and if you want to use ID (this works with multiple processes with the same name) type ID: \n")
    if process == "get-process":
        print(os.system("powershell get-process"))
        process = input("What is the name of your process, if you are unsure, type 'get-process', and find your process: \n")
    else:
        monitorprocess(process)
processes()

And there is some more output with the print, that being "hours" and "days", but that does not really matter in this context.

maybe you should do python script.py > output.txt - and probably it should redirect console output to file (at least it works in cmd.exe or bash on Linux). OR you should use other functions in module subprocess - like subprocess.run() or subprocess.check_output() because with os.system() you can't catch output. — furas
– furas, Commented Jul 7, 2021 at 17:27

furas · Accepted Answer · 2021-07-07 18:14:02Z

1

I can't test it with powershell because I don't use Windows but to catch output you should use other methods in subprocess

ie. subprocess.check_output()

 import subprocess

 output = subprocess.check_output(cmd, shell=True)

 with open('output.txt', 'w') as file:
     file.write(output.decode())

ie. subprocess.run()

 import subprocess
 from subprocess import PIPE

 output = subprocess.run(cmd, shell=True, stdout=PIPE).stdout

 with open('output.txt', 'w') as file:
     file.write(output.decode())

Probably you could even redirect run() directly to file using stdout=

 with open('output.txt', 'w') as file:
     subprocess.run(cmd, shell=True, stdout=file)

Using os.system() you can catch only return code (error code) and you could only do python script.py > output.txt to get text in file output.txt

edited Jul 7, 2021 at 18:14

answered Jul 7, 2021 at 18:05

furas

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1 Comment

eXPRESS Over a year ago

subprocess.run() worked for me, thx.

Theo · Accepted Answer · 2021-07-07 18:06:12Z

0

What you see on screen can be produced by PowerShell.

Try

timespan = os.system(f'powershell New-TimeSpan -Start(Get-process {process}).StartTime | Format-List | Out-String')

This now will not return a TimeSpan object, but rather a multiline string meant to display the properties of the object on screen.

edited Jul 7, 2021 at 18:06

answered Jul 7, 2021 at 12:08

Theo

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4 Comments

NoteSalad Over a year ago

In python I get an error stating: 'Format-List' is not recognized as an internal or external command, operable program or batch file. 255 The same goes for Out-String Although it works in normal Powershell, outside of python

Theo Over a year ago

@NoteSalad I have escaped the pipe characters now. Can you try again please?

Theo Over a year ago

Sorry, I'm not really familiar with python, so I have no idea if you need to escape the pipe characters or not (apparently not..). Perhaps you need to do some more quoting or as @furas suggests, an entirely different way to run a powershell command from python.

NoteSalad Over a year ago

yup, seems like it, thanks for the help htough!

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