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[no audio]

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Friends, here we are going to discuss

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about 'os.system()' of your 'os'

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module. Actually,

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this 'os.system()' is a function because if you observe

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here, I have given parentheses.

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[no audio]

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The purpose of this 'os.system()'

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function from your 'os' module is just to execute

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your operating system commands.

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See as of now, we have seen some of the commands from your

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Python to work with your operating systems,

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like 'os.listdir()', 'removedir()', 'mkdir()',

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'chdir()', 'getcwd()',

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right? But in case if you don't have any command from your

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Python to work with your operating system,

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and if you know the command of your operating system, and

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if you want to execute your operating system command with

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Python, then this 'os.system()' is helpful.

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See there is a command called 'pwd', suppose on your Unix-like

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systems. What is the output you're getting? Current working

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directory or where you are on your terminal, right. See,

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with your 'os' module, right,

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'os.',

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'getcwd' is there, but assume that

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you forgot about this 'os.getcwd', because if you go

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with 'os.', suppose 'listdir()', there are different

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commands, right, from your Python to work with your operating

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system. But by mistake,

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[no audio]

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otherwise, simply assume that I forgot

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about this 'os.getcwd()',

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'os.listdir()', 'os.makedirs()', something like that.

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Then what I can do is, simply I can use 'os.system()',

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[no audio]

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and then I can run my particular operating system commands. See that.

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[no audio]

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And then 'os.system()',

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I can run 'ls' command. See the output.

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[no audio]

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Right. You're able to execute your operating system commands

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with the help of 'os.system()'.

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Not only Linux,

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you can also execute from your Windows as well.

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Let me enter into my Python.

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Let me 'import os'. 'os.system()'.

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[no audio]

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I can run something like 'dir' command.

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Yes, you are getting output.

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Right. 'dir' is the command for

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your Windows operating system to list your directories and

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files in the current location.

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Same thing you can run with your 'os.system()' as well through

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Python. So simply 'os.system()' is helpful to execute

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your operating system commands.

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See, to clear my terminal, right,

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if it is Linux I'm using 'clear' command, if it is Windows

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I have to use 'cls', right. See that what I am doing,

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'os.system()'. Because I am on Linux as of now

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I am running 'os.system("clear")'.

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Now, your terminal is clearing.

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Let me open your Windows terminal. Now,

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I am in Python shell but I want to execute Windows command

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called 'cls'. Yes, you can execute it.

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You know, what is the result of 'cls'?

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It will simply clear your screen.

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Yes, that's what it is doing.

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But if you observe here guys, while running your commands,

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it may be any command, right, see the output. You are getting,

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you are able to display your output directly with the help

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of your 'os.system()', right, at the same time you are getting

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some return code.

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So here you are getting 0, that means whatever the command

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you are running with 'os.system()',

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that is success.

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Right. Not only there, here also

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let me simply run 'os.system()'.

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Now, I am on Unix box.

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I am running 'pwd' command. See the result. You are getting path,

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current working directory, and also you're getting some 0. That is

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the return code from your 'os.system()'.

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If it is 0 then whatever the command you are running, that

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was success, that was successfully executed by your 'os.system()'.

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Let's say I am running 'os.system()', something called 'random'

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command, which is not a valid command

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as per your operating system,

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that's why, see the output what you are getting. You are

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getting some error, along with that return code as non-zero.

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See that. I am writing something like that, 'rt = 'os.system()',

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some 'ls'. Guys if I run in this way, be clear, it's very important,

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whatever the output you are going to get from your 'os.system()'

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with the help of, to run your 'ls' command, that

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output won't go and store into this. Simply the return status

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of this executed syntax, that will store into this 'rt'. That

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means, in case if it is executing successfully then 0 will

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store into this, otherwise non-zero will store into that. Now,

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see the output. So previously whenever if you're running your

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command you are getting output and also some return code,

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but now I am assigning that return code into some variable.

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Now you're getting only output.

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[no audio]

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Make sure that 'os.system()'

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output you're not able to store into any variable.

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You can't store. The only thing, you can directly display your

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output. But what it will store? In case if you assign your

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'os.system()' some command output into a variable,

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what is the value you are going to store into that? Simply,

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simply the executed command status, whether

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it is success or fail, that status you're going to store into

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'rt'. Right. See that. Let me write a simple script

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so that you can understand.

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'vi run_os_cmds'. I am writing 'run_os.py', or

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'os_cmds' instead of this. Just for clarity

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I'm writing 'run_os_cmds.py', or any command also.

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So I can run with the help of 'os',

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I mean 'os.system()'.

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You're also having different procedures guys,

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we will see while going forward. For time being

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it is important, I am working with this.

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See, command is always a string.

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You have to remember that. Suppose my command is, let's say

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date command.

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Right. Now what I am doing is, 'os.system()', then your command.

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So already I stored my command into 'cmd' variable as a string,

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now I can provide that.

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Let me store it and see your script once. Now,

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I am going to run this script. You're getting output.

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[no audio]

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Right. Whenever if you're running your 'os.system()' from

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your Python script, no need to print the result. Automatically

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it is printing the result.

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Right. Now what I am doing is, maybe as of now date command is perfect

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that's why we are getting output, right?

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Maybe I am taking some wrong command. Now see the output.

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[no audio]

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Now whenever if it is wrong command your 'os.system()'

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will give some return codes,

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I want to capture that.

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Let me take rt = 'os.system()', some command. Now,

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I can take some 'if' condition, 'if rt == 0', then I can say that,

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'print()',

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"your", whatever the command you're having, "your cmd was

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success", "successfully executed".

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[no audio]

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'else',

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[no audio]

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'else' because if 'rt' is not equal to 0 means fail, "your

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command was fail".

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[no audio]

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That's it. Very simple no.

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I can capture the return status of this command means if

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this command was success then I can capture

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0 into this 'rt' variable, you can take any variable

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here, not only 'rt'. Simply I'm taking return code,

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that's why I am taking 'rt' as the variable, but you can

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take simply 'x' also.

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Right. Now see the output.

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I'm running your script. Before running

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just open your script, right.

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See this is your script, and now I am running that. See the

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result, "your command was failed".

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[no audio]

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Right. Now see that. What I am doing is,

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[no audio]

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"Your command", right?

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Yeah, I'm going to give now a valid command. Date is

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a valid command, right?

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[no audio]

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Now see that. "your cmd was successfully executed".

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So guys make sure that 'os.system()' is used to execute your

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any operating system commands and while executing your commands

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with 'os.system()' in your Python script by default

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it will print the output of your command on your terminal

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while running your script.

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At the same time it is also going to give

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some return code based on whether your command is success or not.

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If your command was success 'os.system()' will

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give 0 as the code, if your command was failed then your

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'os.system()' command will give return code or code

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as non-zero value. Based on that I can decide whether it is

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success or not.

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[no audio]

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Right. Okay.

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Okay guys, so while going forward we will use this 'os.system()'

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command, and we will write lot of scripts using this

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'os.system()', right?

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Okay, thank you for watching this video.

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[no audio]