38.2 - The dup2 System Call - A C tutorial for redirecting stdin and stdout using system calls. 

By far the best explanation on this topic I have found on the web. The way you visualize, reiterate, and add different examples while switching from code to illustrations is superb.

The best explanation I found online! Excellent!

Greatest work on youtube please make videos on multithreading. Your videos are magic.

Finally some real English ...... God ! My ears ...

great explanation, thank you very much for sharing your knowledge!

Great video and explaination. Now I get it all. Thx a lot

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Thank you! Very clear and detailed!

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Thank you so much, it's really amazing video. What application do you use for drawing on the screen ?

how to reset stdin/out to the terminal?

superb video! What program and device are you using to annotate the screen real time?

Thank you so much!

I don't think you need to use dup2 to implement redirect but I guess he is just using dup2 to show how it works. If you close stdout before calling open what the open function will do is find the lowest file descriptor available (which is now STDOUT) and use that instead of creating a new file descriptor which is FD3 in this example.

Excellent!

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why do you sound like the guy from khanacademy?

how to reset output to stdout?