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[no audio]

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Friends here we are going to

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implement one simple Python Script that is,

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simply how to change current working directory. See changing

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current working directory with Python is very easy.

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Let me enter into my Python 3 terminal, right, and I am going

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to import 'os' module.

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Let me show you that, 'os.', current working directory

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where we are.

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We know we have 'os.getcwd' syntax. Already

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we have seen all these syntaxes in our previous videos, right?

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Fine. Now suppose

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I want to move or change my current working directory to

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something, some location

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I am giving, some path

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I am giving. Now it has been executed. Now

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let me check it where we are now, 'getcwd',

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under 'root' it is see.

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So if you write these three lines, right, then your script is over.

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But sometimes while changing your directory you will get

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some exceptions.

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Let me show you them. Suppose

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what I am doing is, 'chdir("/etc/")'.

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I will do one thing first.

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[no audio]

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So let me move into 'tmp', and let me create

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'hi.txt', and let me create directory.

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[no audio]

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Fine. Now, I am entering into my 'python3'.

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Right. Let's make sure this is Python 3 syntaxes.

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So you have small differences with your Python 3,

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I mean compared to Python 2, right. Fine. First

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let me import 'os' module. Then 'os.getcwd', right?

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Then I am changing into suppose

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"/tmp".

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[no audio]

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Now, what is your current working directory?

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Fine. Now

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anyway we are in '/tmp',

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but just assume that you are in any location but I am trying

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to provide '/tmp',

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and then 'hi.txt'.

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So 'hi.txt' is a file, right?

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We can't move into that. In case you provide by mistake that

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as the path to change, right, through your Python,

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then you are going to get an exception.

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What is that exception?

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'NotADirectory' error, right.

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Just make a note of this.

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So that finally we'll create complete script.

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So this is one of the exception you are going to get. When

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you are going to get that,

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'NotADirectory' exception.

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Now, what I am doing is, 'os.chdir("/tmp/hello.txt").

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[no audio]

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See that. Now what you are getting, 'FileNotFound' error because

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actually whatever the path you are providing, that is not

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present on your host. In that case you are going to get

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exception in this way.

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Right. Now, let me make a note on this as well.

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[no audio]

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Then let me move into one more directory.

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So suppose I have '/etc/httpd', there

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I have something file called 'conf'.

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Now see that. What is the exception you are getting.

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'PermissionError', so 'Permission denied'. Actually have a path but you

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don't have permission to enter into that directory, right?

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So changing directory, working directory is very simple,

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simply 'os.chdir'.

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But while working in your real time you will get these type

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of exceptions. Then whenever if you are writing a Python Script,

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it should work in all scenarios.

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That's why you need to think about all possibility exceptions.

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These are the possible exceptions you have

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for your 'chdir'.

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Now, you need to write a Python Script, right?

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So what I want to do is first I need to 'import os'. First

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I am going to implement this script in terms of, I mean without

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functions. Then after that I will show you in terms of simple

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function, so that you will get practice with your functions as well.

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Okay. Fine. 'import os'. So I am going to read a required path

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from the user. So 'req_path =', just use 'input' syntax.

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So, "Enter your

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change directory", "Enter path to change directory".

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[no audio]

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That's it. Right. Just for user understanding purpose

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we are giving this 'print' message.

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So before going to change, let me print simply,

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[no audio]

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"The current working directory is", so you know, how we can

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get with 'os', 'os.getcwd'.

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Then, now guys see you're going to get an exception, right,

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so you can easily handle with the 'try' and 'except' blocks.

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So what I am doing is, 'try:'

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[no audio]

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'try:', so what I am trying is 'os.chdir

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(req_path)'. So you are going to read the path from the

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input side, right. Now in case if it is works perfectly, then

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I can 'print', simply, "Now your new working directory is", then

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I can say simply 'os.getcwd()'.

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But while changing your path, while changing your directory you're

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going to get some exceptions, right.

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We have already taken those exceptions. Now in case very first

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chance let me take this one.

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The given path is not existing then, then you are going to

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get this exception,

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then I am handling this, 'except', in case 'FileNotFoundError',

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then I can say simply,

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"Please verify

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[no audio]

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given path",

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or "Given path is not a valid path".

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[no audio]

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"Given path is not a valid path". That's it.

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or sometimes you're providing valid path

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but you are going to provide file path, then 'except

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NotADirectory' exception. Then I can say 'print("

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[no audio]

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Given path is a file path.

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So can't change

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[no audio]

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working directory")'. So same information if you want to write

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you can also write in your

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'FileNotFoundError' also. That's it.

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[no audio]

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Right. Then you have one more exception. Even though if you

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provide valid path valid directory path, sometimes you

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may not have access to enter into that directory, then

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'PermissionError', then print simply

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"Sorry,

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[no audio]

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you don't have

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[no audio]

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access to change".

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Okay, "You don't have access to",

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"access for the given

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path. So can't change", you can write any message, whatever you want.

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That's it. Other than this, in case if you get any other,

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any new exception, just to handle that exception, 'except

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Exception as e', let me print that exception. In case if you

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get any new exceptions, then you can handle them,

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you can see them here,

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so that in future you can add them, right? That's it.

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Right. Now let me exit from here, and I am going to write a

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simple Python Script, 'change_directory.py'.

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[no audio]

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That's it.

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Now, let me save it and let me run this with 'python3', so I didn't

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provide shebang line.

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If you want you can provide and directly you can write, by giving

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execution permission

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you can run './'.

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Okay, something error.

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I have given,

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where? Yeah, two quotations. Let me remove one quotation.

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Now, it's fine.

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[no audio]

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So I am going to provide '/etc'.

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Now your new working directory is '/etc'.

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Let me rerun, and I'm going to provide '/etc',

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something like 'xyz'. Now see that, "Given path is not a valid path.

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so can't change working directory". Now, let me provide '/etc,

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something like 'httpd', then 'conf'.

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"Sorry you don't have access for given path.

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So can't change working directory".

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So guys if you observe clearly, changing your working directory

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is very simple code, 'os.chdir'.

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But while changing in your real time, you will get some exceptions,

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so you have to be ready to handle them.

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So now we handle them in our code.

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So this is simply your simple Python Script, but now I

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want to implement same script in terms of functions.

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Anyway, I am not going to write deep functions, simply

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I'm writing very simple function.

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So guys, we know that it's better to start your code

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always with 'if __name'.

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The reason is, whenever if someone is going to import your

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code at that time you can hide your main logic, they can use

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only your 'main' function. So that's it.

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Now, let me simply write,

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anyway, just import your modules at very first

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line, right, then start with 'if __', then

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write your 'main' function.

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So as of now, I'm not going to write any number of functions,

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I am going to write only one function.

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So inside of this function just I am writing this logic. That's it.

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Just for your understanding purpose. That's it.

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Now, let me provide indentations

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otherwise you will get an error,

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[no audio]

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I mean you'll get an indentation error, right?

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[no audio]

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That's it.

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So now your function is over.

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Anyway, as of now I'm not expecting anything from your 'main'

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function to your 'if' condition that's why simply at the end

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I am writing 'return None'.

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That's it. So I commented your previous code. Same code

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just I have it inside of your 'main' function. That's it.

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Right. So guys be clear, whenever if you're trying to write your

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code it's always better to start with your 'if' condition,

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and then some, not only 'main', you can take any function name,

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but generally we'll take 'main'. Just write that 'main' function

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here. That's it.

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Then inside that you write your logic. That's fine.

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Now, let me run it.

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So before going to run let me provide shebang line as well.

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So this is my Python location.

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So I want to provide this at very first line in my code.

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[no audio]

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That's it. Now I am going to provide execution permissions for my script

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Now I can run my script in this way. Now I am providing

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[no audio]

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'Permission denied path'. So I have some path on my host for

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which I don't have access. Now see that.

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Okay. So guys this is the simple way to handle your script

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with exceptions whenever if you want to change your working

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directory through your Python Script, okay.

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Okay guys, thank you for watching this video.

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[no audio]