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How to write powershell output to file? [Python]

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.

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

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.

How to check whether a shell command returned nothing or something

I am writing a script to extract something from a specified path. I am returning those values into a variable. How can i check whether the shell command has returned something or nothing.
My Code:
def any_HE():
global config, logger, status, file_size
config = ConfigParser.RawConfigParser()
config.read('config2.cfg')
for section in sorted(config.sections(), key=str.lower):
components = dict() #start with empty dictionary for each section
#Retrieving the username and password from config for each section
if not config.has_option(section, 'server.user_name'):
continue
env.user = config.get(section, 'server.user_name')
env.password = config.get(section, 'server.password')
host = config.get(section, 'server.ip')
print "Trying to connect to {} server.....".format(section)
with settings(hide('warnings', 'running', 'stdout', 'stderr'),warn_only=True, host_string=host):
try:
files = run('ls -ltr /opt/nds')
if files!=0:
print '{}--Something'.format(section)
else:
print '{} --Nothing'.format(section)
except Exception as e:
print e
I tried checking 1 or 0 and True or false but nothing seems to be working. In some servers, the path '/opt/nds/' does not exist. So in that case, nothing will be there on files. I wanted to differentiate between something returned to files and nothing returned to files.

First, you're hiding stdout.
If you get rid of that you'll get a string with the outcome of the command on the remote host. You can then split it by os.linesep (assuming same platform), but you should also take care of other things like SSH banners and colours from the retrieved outcome.

As perror commented already, the python subprocess module offers the right tools.
https://docs.python.org/2/library/subprocess.html
For your specific problem you can use the check_output function.
The documentation gives the following example:
import subprocess
subprocess.check_output(["echo", "Hello World!"])
gives "Hello World"

plumbum is a great library for running shell commands from a python script. E.g.:
from plumbum.local import ls
from plumbum import ProcessExecutionError
cmd = ls['-ltr']['/opt/nds'] # construct the command
try:
files = cmd().splitlines() # run the command
if ...:
print ...:
except ProcessExecutionError:
# command exited with a non-zero status code
...
On top of this basic usage (and unlike the subprocess module), it also supports things like output redirection and command pipelining, and more, with easy, intuitive syntax (by overloading python operators, such as '|' for piping).

In order to get more control of the process you run, you need to use the subprocess module.
Here is an example of code:
import subprocess
task = subprocess.Popen(['ls', '-ltr', '/opt/nds'], stdout=subprocess.PIPE)
print task.communicate()

python script using subprocess, redirect ALL output to file

I am writing something for static analysis of source code in different languages. As anything has to be open source and callable from command line I now have downloaded one tool per language. So I decided to write a python script listing all source files in a project folder and calling the respective tool.
So part of my code looks like this:
import os
import sys
import subprocess
from subprocess import call
from pylint.lint import Run as pylint
class Analyser:
def __init__(self, source=os.getcwd(), logfilename=None):
# doing initialization stuff
self.logfilename = logfilename or 'CodeAnalysisReport.log'
self.listFiles()
self.analyseFiles()
def listFiles(self):
# lists all source files in the specified directory
def analyseFiles(self):
self.analysePythons()
self.analyseCpps()
self.analyseJss()
self.analyseJavas()
self.analyseCs()
if __name__ == '__main__':
Analyser()
Let's have at a look at the C++ files part (I use Cppcheck to analyse those):
def analyseCpps(self):
for sourcefile in self.files['.cc'] + self.files['.cpp']:
print '\n'*2, '*'*70, '\n', sourcefile
call(['C:\\CodeAnalysis\\cppcheck\\cppcheck', '--enable=all', sourcefile])
The console output for one of the files (it's just a random downloaded file) is:
**********************************************************************
C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc
Checking C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc...
[C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc:18]: (style) The scope of the variable 'oldi' can be reduced.
[C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc:43]: (style) The scope of the variable 'lastbit' can be reduced.
[C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc:44]: (style) The scope of the variable 'two_to_power_i' can be reduced.
(information) Cppcheck cannot find all the include files (use --check-config for details)
Line 1 and 2 coming from my script, lines 3 to 7 coming from Cppcheck.
And this is what I want to save to my log file, for all the other files too. Everything in one single file.
Of course I have searched SO and found some methods. But none is working completely.
First try:
Adding sys.stdout = open(self.logfilename, 'w') to my constructor. This makes line 1 and 2 of the above showed output be written to my log file. The rest is still shown on console.
Second try:
Additionaly, in analyseCpps I use:
call(['C:\CodeAnalysis\cppcheck\cppcheck', '--enable=all', sourcefile], stdout=sys.stdout)
This makes my log file to be:
Checking C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc...
**********************************************************************
C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc
and the console output is:
[C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc:18]: (style) The scope of the variable 'oldi' can be reduced.
[C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc:43]: (style) The scope of the variable 'lastbit' can be reduced.
[C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc:44]: (style) The scope of the variable 'two_to_power_i' can be reduced.
Not what I want.
Third try:
Using Popen with pipe. sys.stdout is back to default.
As preliminary work analyseCpps now is:
for sourcefile in self.files['.cc'] + self.files['.cpp']:
print '\n'*2, '*'*70, '\n', sourcefile
p = subprocess.Popen(['C:\\CodeAnalysis\\cppcheck\\cppcheck', '--enable=all', sourcefile], stdout=subprocess.PIPE)
p.stdout.read()
p.stdout.read() shows only the last line of my desired output (line 7 in code box 3)
Fourth try:
Using subprocess.Popen(['C:\CodeAnalysis\cppcheck\cppcheck', '--enable=all', sourcefile], stdout=open(self.logfilename, 'a+')) just writes the one line Checking C:\CodeAnalysis\testproject\cpp\BiggestUnInt.cc... to my logfile, the rest is shown on the console.
Fifth try:
Instead of subprocess.Popen I use os.system, so my calling command is:
os.system('C:\CodeAnalysis\cppcheck\cppcheck --enable=all %s >> %s' % (sourcefile, self.logfilename))
This results in the same log file as my fourth try. If I type the same command directly in the windows console the result is the same. So I guess it it is not exactly a python problem but still:
If it is on the console there must be a way to put it in a file. Any ideas?
E D I T
Foolish me. I'm still a noob so I forgot about the stderr. That's where the decisive messages are going to.
So now I have:
def analyseCpps(self):
for sourcefile in self.files['.cc'] + self.files['.cpp']:
p = subprocess.Popen(['C:\\CodeAnalysis\\cppcheck\\cppcheck', '--enable=all', sourcefile], stderr=subprocess.PIPE)
with open(self.logfilename, 'a+') as logfile:
logfile.write('%s\n%s\n' % ('*'*70, sourcefile))
for line in p.stderr.readlines():
logfile.write('%s\n' % line.strip())
and it's working fine.
ANOTHER EDIT
according to Didier's answer:
with sys.stdout = open(self.logfilename, 'w', 0) in my constructor:
def analyseCpps(self):
for sourcefile in self.files['.cc'] + self.files['.cpp']:
print '\n'*2, '*'*70, '\n', sourcefile
p = subprocess.Popen(['C:\\CodeAnalysis\\cppcheck\\cppcheck', '--enable=all', sourcefile], stdout=sys.stdout, stderr=sys.stdout)

There are several problems:
you should redirect both stdout and stderr
you should use unbuffered files if you want to mix normal print and the output of launched commands.
Something like this:
import sys, subprocess
# Note the 0 here (unbuffered file)
sys.stdout = open("mylog","w",0)
print "Hello"
print "-----"
subprocess.call(["./prog"],stdout=sys.stdout, stderr=sys.stdout)
print "-----"
subprocess.call(["./prog"],stdout=sys.stdout, stderr=sys.stdout)
print "-----"
print "End"

You need to redirect stderr too, you can use STDOUT or pass the file object to stderr=:
from subprocess import check_call,STDOUT
with open("log.txt","w") as f:
for sourcefile in self.files['.cc'] + self.files['.cpp']:
check_call(['C:\\CodeAnalysis\\cppcheck\\cppcheck', '--enable=all', sourcefile],
stdout=f, stderr=STDOUT)

Try to redirect stdout and stderr to a logfile:
import subprocess
def analyseCpps(self):
with open("logfile.txt", "w") as logfile:
for sourcefile in self.files['.cc'] + self.files['.cpp']:
print '\n'*2, '*'*70, '\n', sourcefile
call(['C:\\CodeAnalysis\\cppcheck\\cppcheck',
'--enable=all', sourcefile], stdout=logfile,
stderr=subprocess.STDOUT)
In this example the filename is hardcoded, but you should be able to change that easily (to your self.logfilename or similar).

Python 2.6 - passing | char into os.system in for loop

I have a list of IP's that I want to run a whois (using the linux tool whois) against and only see the Country option.
Here is my script:
import os
import time
iplist = open('ips.txt').readlines()
for i in iplist:
time.sleep(2)
print "Country: IP {0}".format(i)
print os.system("whois -h whois.arin.net + {0} | grep Country ".format(i))
So I want to display what IP is being ran, then I just want to see the Country info using grep. I see this error when I run it and the grep is not ran:
sh: -c: line 1: syntax error near unexpected token `|'
sh: -c: line 1: ` | grep Country '
this code below works so it must be an issue with my for loop:
print os.system("whois -h whois.arin.net + {0} | grep Country ".format('8.8.8.8'))
What am I doing wrong? Thank you!!!!

You're not stripping trailing newlines from the lines you read from the file. As a result, you are passing to os.system a string like "whois -h whois.arin.net + a.b.c.d\n | grep Country". The shell parses the string as two commands and complains of "unexpected token |" at the beginning of the second one. This explains why there is no error when you use a hand-made string such as "8.8.8.8".
Add i = i.strip() after the sleep, and the problem will go away.

user4815162342 is correct about the issue you are having, but might I suggest you replace os.system with subprocess.Popen? Capturing the output from the system call is not intuitive.. should you want to result to go anywhere but your screen, you'll likely going to have issues
from subprocess import Popen, PIPE
server = 'whois.arin.net'
def find_country(ip):
proc = Popen(['whois', '-h', server, ip], stdout = PIPE, stderr = PIPE)
stdout, stderr = proc.communicate()
if stderr:
raise Exception("Error with `whois` subprocess: " + stderr)
for line in stdout.split('\n'):
if line.startswith('Country:'):
return line.split(':')[1].strip() # Good place for regex
for ip in [i.strip() for i in open('ips.txt').readlines()]:
print find_country(ip)
Python is awesome at string handling- there should be no reason to create a grep subprocess to pattern match the output of a separate subprocess.

Try sh:
import os
import time
import re
import sh
iplist = open('ips.txt').readlines()
for i in iplist:
time.sleep(2)
print "Country: IP {0}".format(i)
print sh.grep(sh.whois(i, h="whois.arin.net"), "Country")

How to redirect stderr in Python?

I would like to log all the output of a Python script. I tried:
import sys
log = []
class writer(object):
def write(self, data):
log.append(data)
sys.stdout = writer()
sys.stderr = writer()
Now, if I "print 'something' " it gets logged. But if I make for instance some syntax error, say "print 'something# ", it wont get logged - it will go into the console instead.
How do I capture also the errors from Python interpreter?
I saw a possible solution here:
http://www.velocityreviews.com/forums/showpost.php?p=1868822&postcount=3
but the second example logs into /dev/null - this is not what I want. I would like to log it into a list like my example above or StringIO or such...
Also, preferably I don't want to create a subprocess (and read its stdout and stderr in separate thread).

I have a piece of software I wrote for work that captures stderr to a file like so:
import sys
sys.stderr = open('C:\\err.txt', 'w')
so it's definitely possible.
I believe your problem is that you are creating two instances of writer.
Maybe something more like:
import sys
class writer(object):
log = []
def write(self, data):
self.log.append(data)
logger = writer()
sys.stdout = logger
sys.stderr = logger

You can't do anything in Python code that can capture errors during the compilation of that same code. How could it? If the compiler can't finish compiling the code, it won't run the code, so your redirection hasn't even taken effect yet.
That's where your (undesired) subprocess comes in. You can write Python code that redirects the stdout, then invokes the Python interpreter to compile some other piece of code.

I can't think of an easy way. The python process's standard error is living on a lower level than a python file object (C vs. python).
You could wrap the python script in a second python script and use subprocess.Popen. It's also possible you could pull some magic like this in a single script:
import os
import subprocess
import sys
cat = subprocess.Popen("/bin/cat", stdin=subprocess.PIPE, stdout=subprocess.PIPE)
os.close(sys.stderr.fileno())
os.dup2(cat.stdin.fileno(), sys.stderr.fileno())
And then use select.poll() to check cat.stdout regularly to find output.
Yes, that seems to work.
The problem I foresee is that most of the time, something printed to stderr by python indicates it's about to exit. The more usual way to handle this would be via exceptions.
---------Edit
Somehow I missed the os.pipe() function.
import os, sys
r, w = os.pipe()
os.close(sys.stderr.fileno())
os.dup2(w, sys.stderr.fileno())
Then read from r

To route the output and errors from Windows, you can use the following code outside of your Python file:
python a.py 1> a.out 2>&1
Source: https://support.microsoft.com/en-us/help/110930/redirecting-error-messages-from-command-prompt-stderr-stdout

Since python 3.5 you can use contextlib.redirect_stderr
with open('help.txt', 'w') as f:
with redirect_stdout(f):
help(pow)

For such a request, usually it would be much easier to do it in the OS instead of in Python.
For example, if you're going to run "a.py" and record all the messages it will generate into file "a.out", it would just be
python a.py 2>&1 > a.out
The first part 2>&1 redirects stderr to stdout (0: stdin, 1:stdout, 2:stderr), and the second redirects that to a file called a.out.
And as far as I know, this command works in Windows, Linux or MacOS! For other file redirection techniques, just search the os plus "file redirection"

I found this approach to redirecting stderr particularly helpful. Essentially, it is necessary to understand if your output is stdout or stderr. The difference? Stdout is any output posted by a shell command (think an 'ls' list) while sterr is any error output.
It may be that you want to take a shell commands output and redirect it to a log file only if it is normal output. Using ls as an example here, with an all files flag:
# Imports
import sys
import subprocess
# Open file
log = open("output.txt", "w+")
# Declare command
cmd = 'ls -a'
# Run shell command piping to stdout
result = subprocess.run(cmd, stdout=subprocess.PIPE, shell=True)
# Assuming utf-8 encoding
txt = result.stdout.decode('utf-8')
# Write and close file
log.write(txt)
log.close()
If you wanted to make this an error log, you could do the same with stderr. It's exactly the same code as stdout with stderr in its place. This pipes an error messages that get sent to the console to the log. Doing so actually keeps it from flooding your terminal window as well!
Saw this was a post from a while ago, but figured this could save someone some time :)

import sys
import tkinter
# ********************************************
def mklistenconsswitch(*printf: callable) -> callable:
def wrapper(*fcs: callable) -> callable:
def newf(data):
[prf(data) for prf in fcs]
return newf
stdoutw, stderrw = sys.stdout.write, sys.stderr.write
funcs = [(wrapper(sys.stdout.write, *printf), wrapper(sys.stderr.write, *printf)), (stdoutw, stderrw)]
def switch():
sys.stdout.write, sys.stderr.write = dummy = funcs[0]
funcs[0] = funcs[1]
funcs[1] = dummy
return switch
# ********************************************
def datasupplier():
i = 5.5
while i > 0:
yield i
i -= .5
def testloop():
print(supplier.__next__())
svvitch()
root.after(500, testloop)
root = tkinter.Tk()
cons = tkinter.Text(root)
cons.pack(fill='both', expand=True)
supplier = datasupplier()
svvitch = mklistenconsswitch(lambda text: cons.insert('end', text))
testloop()
root.mainloop()

Python will not execute your code if there is an error. But you can import your script in another script an catch exceptions. Example:
Script.py
print 'something#
FinalScript.py
from importlib.machinery import SourceFileLoader
try:
SourceFileLoader("main", "<SCRIPT PATH>").load_module()
except Exception as e:
# Handle the exception here

To add to Ned's answer, it is difficult to capture the errors on the fly during the compilation.
You can write several print statements in your script and you can stdout to a file, it will stop writing to the file when the error occurs. To debug the code you could check the last logged output and check your script after that point.
Something like this:
# Add to the beginning of the script execution(eg: if __name__ == "__main__":).
from datetime import datetime
dt = datetime.now()
script_dir = os.path.dirname(os.path.abspath(__file__)) # gets the path of the script
stdout_file = script_dir+r'\logs\log'+('').join(str(dt.date()).split("-"))+r'.log'
sys.stdout = open(stdout_file, 'w')
This will create a log file and stream the print statements to the file.
Note: Watch out for escape characters in your filepath while concatenating with script_dir in the second line from the last in the code. You might want something similar to raw string. You can check this thread for this.