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[no audio]

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Friends here we are going to

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write a simple Python script with your 'subprocess' module.

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The requirement is, find bash version of Linux OS. See, if I

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take my Linux OS or terminal, you know, you have bash on

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your Unix-like systems and if you run 'bash --version'

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you are getting some output.

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But here what I need, I need this value, only 4.2.46.

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That is actually my version, my bash version.

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I need that output only.

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I don't want entire output.

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See before going to run your command with your Python, you

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have to think about your requirement.

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I mean whether you want to run simply your command, or you

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also need some modifications on your output.

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If you want to run simply your command, then just go and use

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'os.system()'. That is very simple one.

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But on the output if you need some modifications, as of now

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see that, we need to get this output, from this we want only

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this 4.2.46.

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That means we need some modifications on your output.

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That's why just go and run your command using 'subprocess' module.

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Right. See, now

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I am going to write a Python script just to get bash version,

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'bash_version.py'. Guys, I am going to 'import subprocess' module.

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[no audio]

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See, before going to write your Python scripts using

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'subprocess', right,

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you just keep in your hand this document. Already

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we have that from our previous video. For time being directly

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I'm copying this line, but you people don't copy and paste

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the code here. You just try to write, type your code

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so that you will clearly, it is easy to remember your code, right,

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your syntaxes for your 'subprocess'.

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Now actually 'bash --version'

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command is not depending on any environment variables,

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that's why I can take simply 'cmd = False',

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sorry, I mean 'shell = False'. If I take 'shell = False',

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you know, you have to take your command as a list.

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So 'bash --version',

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so how to get a command as a list means, once again I'm showing

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that. Just to go to your Python terminal, take your Windows command

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as it is, I mean windows or Unix-like systems,

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[no audio]

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then try to split this in this way,

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then you are getting some output. That is nothing but your

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list for 'shell = False'.

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That's what I am doing here directly because as of now

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I know the required thing, so that's why directly I am writing

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'bash --version' as a list.

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Fine. After running your command, right,

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it may take some time to execute your command. Anyway,

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'bash --version' is a very simple command.

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It won't take much time. You don't need to wait, but it is a

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better practice to use

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'sp.wait' because sometimes whenever you are going to

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use some SSH command it will take some time to execute your

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commands. That's why just try to make a habit that using

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'sp.wait' in your code. Then find out your output and

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error. So, you know how to get your output and error simply by

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communicating with your

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[no audio]

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'sp'. That's it. Now guys, see based on 'rc' code

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I can say that whether your command was success or failed, right?

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Let me do one thing.

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'If rc', if it is equal to 0, then I can say that, strongly

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I can say

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'print

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[no audio]

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("out is :"). So what is the output?

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'o'. That is the variable we have taken. 'else' means, if

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'rc' code is not equal to 0 means there was a fail.

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So, "command was failed

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[no audio]

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with an error

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[no audio]

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and error is : ".

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[no audio]

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So error is 'e' we

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are taking. But you can take any variable, right?

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Let me save this, and run the code.

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[no audio]

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Let me run this with 'python3'.

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We need 'python3', right?

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[no audio]

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Right. You are getting your output.

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[no audio]

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Right. Now what I am doing is I am going to take a invalid command.

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Instead of your 'bash --version' if I run '- bash version',

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you're getting an invalid syntax.

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I mean command is not executing properly, right?

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That is actually not a valid command.

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So that's why what I am doing is, just I am taking your list

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bash, then instead of '--version', I am taking, you should

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not take, just to show that whether our code is working properly

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or not for that I am taking this one.

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[no audio]

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Let me show your code once, and then let me run your code,

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see, "Command was failed and error is : bash: version:

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No such file or directory."

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So something wrong with your command.

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So we know that what is wrong here.

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That's why be careful whenever if you are taking your commands.

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[no audio]

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So same command, you can also run by using 'shell = True', by

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simply taking your command as a string, but on Windows,

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please prefer 'shell = True' always.

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Okay. Fine.

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So guys, as of now you are getting your output with your Python,

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but requirement is, I don't want to get this entire output

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right? I need only this one.

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That's why what I'm doing is,

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first of all I'm going to convert your entire output into

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a list. You can convert your output, which is from your 'sp', right,

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'splitlines',

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[no audio]

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by using that you can get your output as a list. See that

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you are getting as a list.

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[no audio]

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Right. Now what I am doing is, I am going to print your line one

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by one. Just observe the logic. So I don't want to print in this way.

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What I am doing is I, am taking one by one value from

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your list which has been created from your output, simply

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'for each_line in o.splitlines()'.

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Simply I am printing 'each_line'.

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See that. See the logic, right. The same way you just practice

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it guys so that it will be easy for you to understand this code.

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Yes, again you are getting your entire output.

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But I want to print the lines which are having only 'version.

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Now, it's simple.

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[no audio]

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See that. What I am doing is,

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'if Version', in

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line, in your 'each_line' then only print that line,

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otherwise don't print that line.

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[no audio]

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Now, see the logic what you're going to get your output.

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[no audio]

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Yes, you are getting these two lines.

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[no audio]

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Right, but what you need? You need first line as of now, right,

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I mean version. So as of now, you don't know RegEx concept,

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what we will do is, yeah based on 'release'

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I will take. 'if version and release', both words are there in

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a given line then only I want to print that. See guys, I'm

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going to use now here your logical operator called 'and'.

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'if version in each_line and', then 'release'. 'version' as well

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as 'release' both I should have in my line, then only I want

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to print that line. Guys,

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you need to understand about logical operator

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'and'. When you have to take 'and' means, see my requirement

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is, this thing should be true,

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this thing should be true,

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whenever these two are true at that time only

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I want to execute my 'if' condition. So in that case you need

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to club your two conditions with the help of 'and' operator.

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So if both are true then only your final result will be true

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if you use 'and' operator. But if you take 'or' operator no,

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you are going to get again two lines. Just check it so that

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you can understand. Now, let me run it and see the output.

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Now you're getting only one line which is having 'version'

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as well as 'release', but I need this part, right? I need this part.

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So what I am doing is, guys, as of now you don't know about RegEx

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that's why I am doing so many steps. Later

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we will see again with RegEx.

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It's very simple.

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As of now don't concentrate on RegEx, just see the logic what I am doing.

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[no audio]

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Right. So now one, two, three, fourth part you are getting as, I mean

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index four is your required output as of now. Let me take

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this. From this I am taking index 3 value.

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[no audio]

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That's it. But I need only 4.2.46. Then again split this with the

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help of this parentheses.

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See that. What I am doing is, again I am splitting your output

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based on this parentheses symbol.

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[no audio]

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Where is it?

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[no audio]

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That's it.

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And then I am taking index 0. Just see first without this

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one what is the output you're getting.

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If I split that output with the help of parentheses what

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we are getting? You are getting a list which consists of 4.2.46.

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And then second value is something, but I need this value

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that's why just take index as 0.

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[no audio]

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Let me write that index 0. So this is the final requirement

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through which you are going to get your bash version 4.2.46.

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Right. So guys successfully we implemented a code called

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getting bash version using Python on your Unix-like systems.

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Right. So guys, this is not that much important.

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But the thing is how you are using your 'subprocess' for your

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requirement, that is important. Getting bash version is not

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the important thing, right. How you are implementing your Unix

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command to get your bash version using your Python, that is

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important. So that's why I have given this example, right.

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Now before going to next video, please.

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please try to find a java

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version using your Python. Yeah, for Java

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you need to take only one '-', right. If you run your code

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I need to get only 1.7.0_211.

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So before going to next video, please, please try to implement

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by yourselves this output.

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[no audio]

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I need to, if I run, if I provide this command for my 'subprocess',

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I mean for my Python script I need to get version as 1.7.0_211

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And just I am giving one clue, in case if you are not getting

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any output. Please see your error as well, see your output and error, and

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try to implement your logic to get your Java -version. So

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why I am giving this example is you have one important point

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with your Java - version command whenever if you are running

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with your Python.

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Right. So before coming to next video, please try to implement the

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code to get your Java version using your Python by executing

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your command with the help of 'subprocess' module, right?

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Okay guys, thank you for watching this video.

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[no audio]