Resources

 by ken

How to close Windows process with python

When automating some tasks in Windows OS, you may wonder how to automatically close Windows process if you do not have the direct control of the running application or when the application is just running for too long time. In this article, I will be sharing with you how to close the Windows process with some python library, to be more specific, the pywin32 library.

Prerequisites

You will need to install the pywin32 library if you have not yet installed:

pip install pywin32

Find the process name from Windows Task Manager

You will need to first find out the application name which you intend to close, the application name can be found from the Windows task manager. E.g. If you expand the “Windows Command Processor” process, you can see the running process is “cmd.exe”.

python close Windows process

Let’s get started with the code!

Import the below modules that we will be using later:

from win32com.client import GetObject
from datetime import datetime

import os

And we need to get the WMI (Windows Management Instrumentation) service via the below code, where we can further access the window processes. For more information about WMI, please check this.

WMI = GetObject('winmgmts:')

Next, we will use the WMI SQL query to get the processes from the Win32_Process table by passing in the application name. Remember we have already found the application name earlier from the task manager.

 

for p in WMI.ExecQuery('select * from Win32_Process where Name="cmd.exe"'):
    #the date format is something like this 20200613144903.166769+480
    create_dt, *_ = p.CreationDate.split('.')
    diff = datetime.now() - datetime.strptime(create_dt,'%Y%m%d%H%M%S')

There are other properties such as Description, Status, Executable Path, etc. You can check the full list of the process properties from this win32-process documentation. Here we want to base on the creation date to calculate how much time the application has been running to determine if we want to kill it.

Assuming we need to close windows process after it is running for 5 minutes.

    if diff.seconds/60 > 5:		
        print("Terminating PID:", p.ProcessId)
	os.system("taskkill /pid "+str(p.ProcessId))

With this taskkill command, we will be able to terminate all the threads under this Windows process peacefully.

Conclusion

The pywin32 is super powerful python library especially when dealing with the Windows applications. You can use it to read & save attachments from outlook, send emails via outlook , open excel files and some more. Do have a check on these articles.

As per always, welcome any comments or questions.

in Automation / Python / Resources 4 comments
auto switch browser tabs
 by ken

How to auto switch browser tabs

Imagine you have a big monitor and you would like to display something from multiple web links, would it be nice if there is a way to auto switch between the multiple browser tabs in a fixed period? In this article, I will be sharing with you how to auto switch browser tabs via selenium, an automated testing tool.

There is a very detailed documentation on the python selenium library, you may want to check this document as the starting point. For this article, I will just walk through the complete code for this automation, so that you can use it as a reference in case you are tying to implement something similar.

Let’s get started!

To auto launch the browser, we need to first download the web driver for the browser. For instance, if you are using chrome browser, you may download the driver file here. Do check your browser version to make sure you download the driver for the correct version.

As the prerequisite, you will also need to run the below command to install the selenium package in your working environment.

pip install selenium

Launch the browser

Then import all the necessary modules into your script. For this article, we will need to use the below modules:

from selenium import webdriver
from selenium.webdriver.chrome.options import Options
from selenium.common.exceptions import SessionNotCreatedException

import time
import os, sys

Let’s assume we want to display the below 3 links in your browser and make them auto switching between each other:

url_1 = "https://www.google.com/maps/@1.3085909,103.8403575,14z"
url_2 = "https://weather.com/en-SG/weather/today"
url_3 = "https://edition.cnn.com/"

Assuming you’ve already downloaded the chrome driver file and put it into the current script folder. Then let’s start to initiate the web driver to launch the browser:

options = Options()
options.add_experimental_option('useAutomationExtension', False)

try:	
	driver = webdriver.Chrome(executable_path=os.getcwd() + "\\chromedriver.exe", options=options)
except SessionNotCreatedException as e:
	print(e)
	print("please upgrade the chromedriver.exe from https://chromedriver.chromium.org/downloads")
	sys.exit(1)

You may wonder why we need a options parameter here?  It’s actually optional, but you may see the “Loading of unpacked extensions is disabled by the administrator” warning without setting useAutomationExtension to False. There are plenty of other options to control the browser behavior, check here for the documentation.

As frequently you will see there is a new version of chrome, and it may not work with old driver file anymore. So, it’s better we catch this exception and show some error message to guide users to upgrade the driver.

You can set the chrome window position by doing the below, but it does not matter if you wish to maximize the window later.

driver.set_window_position(2000, 1)

Let’s open the first link and maximize our window (This also can be done by options.addArguments("start-maximized")). And we want to execute some JavaScript to zoom out a bit so that we can see clearly.

#open window 1
driver.get(url_1)
driver.maximize_window()
driver.execute_script("document.body.style.zoom='120%'")
time.sleep(1)

To open the second tab, we need to use JavaScript to open a blank tab, and switch the active tab to the second tab. The driver.window_handles keeps a list of handlers for the opened windows, so window_handles[1] refers to the second tab.

driver.execute_script("window.open('');")
driver.switch_to.window(driver.window_handles[1])

Next, we will open the second link. And for this tab, let’s scroll down 300px to skip the ads second at the page header.

#open second link
driver.get(url_2)
driver.execute_script("document.body.style.zoom='90%'")
driver.execute_script("window.scrollBy(0,300);")
time.sleep(1)

Similarly, we can open the third tab with the below code:

#open window 3
driver.execute_script("window.open('');")
driver.switch_to.window(driver.window_handles[2])
driver.get(url_3)		
driver.execute_script("document.body.style.zoom='90%'")
driver.execute_script("window.scrollBy(0,200);")
time.sleep(1)

Auto switch between tabs

Once everything is ready, we shall write the logic to auto switch between the different tabs at certain interval. To do that, we need to know how to perform the below 3 things:

  • Identify what is the active link showing now

We can use driver.title attribute to check if the page title contains certain keyword for the particular website, so that we know which page is active now

  • Switch to a new tab

We can continue to use driver.switch_to.window to switch the tab, but we need to have logic to determine which is the next tab we want to switch to

  • Refresh the page (in case there is any updates)

We can use driver.refresh() to refresh the page, but we will lose the setting such as zooming in/out, so we need to set it again

So let’s take a look at the complete code:

nextIndex = 2

start = time.time()

while True:
	
	#stop running after 5 minutes
	if (time.time() - start >= 5*60):
		break
		
	if "Google Maps" in driver.title:
		driver.refresh()
		driver.execute_script("document.body.style.zoom='120%'")
		time.sleep(3)
		nextIndex = 0 if nextIndex + 1 > 2 else nextIndex + 1
		
	elif "CNN" in driver.title:
		driver.refresh()
		driver.execute_script("document.body.style.zoom='90%'")
		time.sleep(5)
		nextIndex = 0 if nextIndex + 1 > 2 else nextIndex + 1
		
	elif "Weather" in driver.title:
		driver.refresh()
		driver.execute_script("document.body.style.zoom='90%'")
		time.sleep(2)
		nextIndex = 0 if nextIndex + 1 > 2 else nextIndex + 1
		
	driver.switch_to.window(driver.window_handles[nextIndex])

So each of the tab will be active for a few seconds before switching to the next tab. And after 5 minutes, this loop will be stopped.

If we wish to close all tabs at the end of the script, we can perform the below:

for window in driver.window_handles:
	driver.switch_to.window(window)
	driver.close()

So that’s it and congratulations that you have completed a new automation project to auto switch browser tabs for Chrome. As per always, welcome any comments or questions.

in Automation / Python / Resources 0 comments
python send email with attachment via smtplib
 by ken

How to send email with attachment via python smtplib

In one of my previous article, I have discussed about how to send email from outlook application. That has assumed you have already installed outlook and configured your email account on the machine where you want to run your script. In this article, I will be sharing with you how to automatically send email with attachments via lower level API, to be more specific, by using python smtplib where you do not need to set up anything in your environment to make it work.

For this article, I will demonstrate to you to send a HTML format email from a gmail account with some attachment. So besides the smtplib module, we will need to use another two modules – ssl and email.

Let’s get started!

First, you will need to find out the SMTP server and port info to send email via google account. You can find this information from this link. For your easy reading, I have captured in the below screenshot.

codeforests - google smtp server configuration info

So we are going to use the server: smtp.gmail.com and port 587 for our case. (you may search online to find out more info about the SSL & TLS, we will not discuss much about it in this article)

Let’s start to import all the modules we need:

import smtplib, ssl
from email.mime.multipart import MIMEMultipart 
from email.mime.text import MIMEText 
from email.mime.application import MIMEApplication

As we are going to send the email in HTML format (which are you able to unlock a lot features such as adding in styles, drawing tables etc.), we will need to use the MIMEText. And also the MIMEMultipart and MIMEApplication for the attachment.

Build up the email message

To build up our email message, we need to create mixed type MIMEMultipart object so that we can send both text and attachment. And next, we shall specify the from, to, cc and subject attributes.

smtp_server = 'smtp.gmail.com'
smtp_port = 587 
#Replace with your own gmail account
gmail = 'yourmail@gmail.com'
password = 'your password'

message = MIMEMultipart('mixed')
message['From'] = 'Contact <{sender}>'.format(sender = gmail)
message['To'] = 'contact@company.com'
message['CC'] = 'contact@company.com'
message['Subject'] = 'Hello'

You probably do not want anybody can see your hard coded password here, you may consider to put this email account info into a separate configuration file. Check my another post on the read/write configuration files.

For the HTML message content, we will wrap it into the MIMEText, and then attach it to our MIMEMultipart message:

msg_content = '<h4>Hi There,<br> This is a testing message.</h4>\n'
body = MIMEText(msg_content, 'html')
message.attach(body)

Let’s assume you want to attach a pdf file from your c drive, you can read it in binary mode and pass it into MIMEApplication with MIME type as pdf. Take note on the additional header where you need to specify the name your attachment file.

attachmentPath = "c:\\sample.pdf"
try:
	with open(attachmentPath, "rb") as attachment:
		p = MIMEApplication(attachment.read(),_subtype="pdf")	
		p.add_header('Content-Disposition', "attachment; filename= %s" % attachmentPath.split("\\")[-1]) 
		message.attach(p)
except Exception as e:
	print(str(e))

If you have a list of the attachments, you can loop through the list and attach them one by one with the above code.

Once everything is set properly, we can convert the message object into to a string:

msg_full = message.as_string()

Send email

Here comes to the most important part, we will need to initiate the TLS context and use it to communicate with SMTP server.

context = ssl.create_default_context()

And we will initialize the connection with SMTP server and set the TLS context, then start the handshaking process.

Next it authenticate our gmail account, and in the send mail method, you can specify the sender, to and cc (as a list), as well as the message string. (cc is optional)

with smtplib.SMTP(smtp_server, smtp_port) as server:
	server.ehlo()  
	server.starttls(context=context)
	server.ehlo()
	server.login(gmail, password)
	server.sendmail(gmail, 
				to.split(";") + (cc.split(";") if cc else []),
				msg_full)
	server.quit()

print("email sent out successfully")

Once sendmail completed, you will disconnect with the server by server.quit().

With all above, you shall be able to receive the email triggered from your code. You may want to wrap these codes into a class, so that you can reuse it as service library in your multiple projects.

 

As per always, please share if you have any questions or comments.

in Automation / Resources 6 comments
python cache
 by ken

How to print colored message on command line terminal window

When you are developing a python script with some output messages printed on the terminal window, you may find a little bit boring that all the messages are printed in black and white, especially if some messages are meant for warning, and some just for information only. You may wonder how to print colored message to make them look differently, so that your users are able to pay special attention to those warning or error messages.

In this article, I will be sharing with you a library which allows you to print colored message in your terminal.

Let’s get started!

The library I am going to introduce called colorama, which is a small and clean library for styling your messages in both Windows, Linux and Mac os.

Prerequisite :

You will need to install this library, so that you will be able to run the following code in this article.

pip install colorama

To start using this library, you will need to import the modules, and call the init() method at the beginning of your script or your class initialization method.

import colorama
from colorama import Fore, Back, Style
colorama.init()

Print colored message with colorama

The init method also accepts some **kwargs to overwrite it’s default behaviors. E.g. by default, the style will not be reset back after printing out a message,  and the subsequent messages will be following the same styles. You can pass in autoreset = true to the init method, so that the style will be reset after each printing statement.

Below are the options you can use when formatting the font, background and style.

Fore: BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE, RESET.
Back: BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE, RESET.
Style: DIM, NORMAL, BRIGHT, RESET_ALL

To use it in your message, you can do as per below to wrap your messages with the styles:

print(Fore.CYAN + "Cyan messages will be printed out just for info only" + Style.RESET_ALL)
print(Fore.RED + "Red messages are meant to be to warning or error" + Style.RESET_ALL)
print(Fore.YELLOW + Back.GREEN +  "Yellow messages are debugging info" + Style.RESET_ALL)

This is how it would look like in your terminal:

Python printed colored message with colorama

As I mentioned earlier, if you don’t set the autoreset to true, you will need to reset the style at the end of your each message, so that different message applies different styles.

What if you want to apply the styles when asking user’s input ? Let’s see an example:

print(Fore.YELLOW)
choice = input("Enter YES to confrim:")
print(Style.RESET_ALL)
if str.upper(choice) in ["YES",'Y']:
    print(Fore.GREEN + "You have just confirmed to proceed." + Style.RESET_ALL)
else:
    print(Fore.RED + "You did not enter yes, let's stop here" + Style.RESET_ALL)

By wrapping the input inside Fore.YELLOW and Style.RESET_ALL, whatever output messages from your script or user entry, the same style will be applied.

Let’s put all the above into a script and run it in the terminal to check how it looks like.

Python printed colored message with colorama

Yes, that’s exactly what we want to achieve! Now you can wrap your printing statement into a method e.g.: print_colored_message, so that you do not need to repeat the code everywhere.

As per always, please share if you have any comments or questions.

 

in Resources 0 comments
python unpack objects
 by ken

Python how to unpack tuple, list and dictionary

There are various cases that you want to unpack your python objects such as tuple, list or dictionary into individual variables, so that you can easily access the individual items. In this article I will be sharing with you how to unpack these different python objects and how it can be useful when working with the *args and **kwargs in the function.

Let’s get started.

Unpack python tuple objects

Let’s say we have a tuple object called shape which describes the height, width and channel of an image, we shall be able to unpack it to 3 separate variables by doing below:

shape = (500, 300, 3)
height, width, channel = shape
print(height, width, channel)

And you can see each item inside the tuple has been assigned to the individual variables with a meaningful name, which increases the readability of your code. Below is the output:

500 300 3

It’s definitely more elegant than accessing each items by index, e.g. shape[0], shape[1], shape[2].

What if we just need to access a few items in a big tuple which has many items? Here we need to introduce the _ (unnamed variable) and * (unpack arbitrary number of items)

For example,  if we just want to extract the first and the last item from the below tuple, we can let the rest of the items go into a unnamed variable.

toto_result = (4,11,14,23,28,47,24)
first, *_, last = toto_result
print(first, last)

So the above will give the below output:

4 24

If you are curious what is inside the “_”, you can try to print it out. and you would see it’s actually a list of the rest of items between the first and last item.

[11, 14, 23, 28, 47]

The most popular use case of the packing and unpacking is to pass around as parameters to function which accepts arbitrary number of arguments (*args). Let’s look at an example:

def sum(*numbers):
    total = 0
    for n in numbers:
        total += n
    return total

For the above sum function, it accepts any number of arguments and sum up the values. The * here is trying to pack all the arguments passed to this function and put it into a tuple called numbers. If you are going to sum up the values for all the items in toto_result, directly pass in the toto_result would not work.

toto_resut = (4,11,14,23,28,47,24)
#sum(toto_result) would raise TypeError

So what we can do is to unpack the items from the tuple then pass it the sum function:

total = sum(*toto_resut)
print(total)
#output should be 151

Unpack python list objects

Unpacking the list object is similar to the unpacking operations on tuple object. If we replace the tuple to list in the above example, it should be working perfectly.

shape = [500, 300, 3]
height, width, channel = shape
print(height, width, channel)
#output shall be 500 300 3

toto_result = [4,11,14,23,28,47,24]
first, *_, last = toto_result
print(first, last)
#output shall be 4 24

total = sum(*toto_resut) 
print(total) 
#output should be also 151

Unpack python dictionary objects

Unlike the list or tuple, unpacking the dictionary probably only useful when you wants to pass the dictionary as the keyword arguments into a function (**kwargs).

For instance, in the below function, you can pass in all your keyword arguments one by one.

def print_header(**headers):
    for header in headers:
        print(header, headers[header])

print_header(Host="Mozilla/5.0", referer = "https://www.codeforests.com")

Or if you have a dictionary like below, you can just unpack it and pass to the function:

headers = {'Host': 'www.codeforests.com', 'referer' : 'https://www.codeforests.com'}
print_header(**headers)

It will generate the same result as previously, but the code is more concise.

Host www.codeforests.com
referer https://www.codeforests.com

With this unpacking operator, you can also combine multiple dictionaries as per below:

headers = {'Host': 'www.codeforests.com', 'referer' : 'https://www.codeforests.com'}
extra_header = {'user-agent': 'Mozilla/5.0'}

new_header = {**headers, **extra_header}

The output of the new_header will be like below:

{'Host': 'www.codeforests.com',
 'referer': 'https://www.codeforests.com',
 'user-agent': 'Mozilla/5.0'}

Conclusion

The unpacking operation is very usefully especially when dealing with the *args and **kwargs. There is one thing worth noting on the unamed variable (_) which I mentioned in the previous paragraph. Please use it with caution, as if you notice, the python interactive interpreter also uses _ to store the last executed expression. So do take note on this potential conflict. See the below example:

codeforests interactive interpreter conflicts

As per always, welcome any comments or questions.

in Python / Resources 0 comments