Linux Crash Course - Data Streams (stdin, stdout & stderr)

In this episode of Linux Crash Course, we'll go over data streams. Specifically, Standard Output (stdout), Standard Input (stdin), and Standard Error (stderr). We'll also take a look at how to redirect specific data streams, so you can easily separate errors from output.
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Time Codes
00:00 - Intro
00:41 - Quick note regarding input/output
01:17 - The three data streams (standard input, standard output, and standard error)
03:06 - Example of Standard Error (stderr)
03:47 - Using the echo command to find the return code
05:54 - Example of both standard output and standard error from one command
07:47 - Splitting standard output and standard error
09:06 - Number designations for stdin, stdout, and stderr
10:24 - Sending stdout and stderr to different files
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[@RayBitton]

And that's why I'm proud of myself... I never think I know everything. I'm a linux administrator as part of my day job and I think I got a good amount of experience with the command line but reading the title of the video made me think "Maybe I'll learn something new about stdout and stderr". I wasn't wrong. "find /etc -type f > ~/results.txt 2> ~/errors.txt" Never knew or thought about splitting the streams. THANK YOU FOR THAT! So useful.

[@satysin630]

When I am introducing someone to the command line this is my go to example of where the command line interface still wins out over a graphical program. The beauty is the application(s) being used don't need to be changed in any way as it is the shell that handles it all for you (providing the applications output to stdout and stderr properly). I once worked with someone that was very "ugh I hate the command line, it's not the 1980s anymore, GUI is always better" so I asked then to do just what you did. Output valid results to one file and errors to another. The only way he could do it was manually and by actually looking then copy/paste the errors to a separate file as none of his graphical tools could filter output (they would just save everything to a single file) so would require the application itself be updated to include such functionality. It didn't totally win him over but it at least shut him up as he knew I would always bring that example up if he ever went on a "GUI is better" rant again 😂Truth is you use the right tool for the job, sometimes that *is* a GUI application but sometimes it's a CLI one so knowing how to best use the tools available is important. Great video 👍

[@clblanchard08]

I've been using linux for years and never really understood this. Thank you so much!

[@andymann6061]

Same here - I was grappling with it just a couple of days ago, but Jay explains it perfectly.

[@sgt.chutney5206]

Another awesome video Jay, you are a great teacher. I would love to see a beginners guide to regular expressions. Thanks!

[@Andy.N-_-]

Love these vids that teach me some of the basics we keep forgetting well done and thank you

[@tilla455]

Great tutorial again. Thank you! Your videos have helped me with work on a daily bases

[@TheRexhim]

Thank you! I needed clarification on this!

[@DL-xf3ur]

Awesome as always Jay! Thanks!

[@piusvictor8780]

You are teaching style is amazing brother ✨✨✨ one love from Tanzania, thanks for sharing, your tutorial are highly recommended to anyone interested with learning Linux.

[@davehodsdon3533]

Great information. Thank you, Jay.

[@itay1207]

YOUR EXPELTAION WAS SO CLEAR AND GOOD.WAS EASY TO UNDERSTAND !THANKS

[@polliluiz]

You’re amazing Jay. Thank you for all of your videos. It’s really the best

[@LearnLinuxTV]

No. YOU are amazing.

[@dfurmans]

Thanks for a great clarification!

[@anthonyverzosa1292]

Thank you very much for this wonderful lesson.

[@jorgepadron2426]

Excellent, as always!

[@greob]

I was expecting you to talk about how to output both stdout AND stderr to a file. For anyone wondering we do it like this: find /etc -type f > combined.txt 2>&1

[@jyvben1520]

not working on raspberry pi, "> combined.txt 2>&1" does work.

[@greob]

@@jyvben1520 yeah it's possible some shells parse it differently, and I suppose that is the correct way of doing it. I'll edit my original comment.

[@perminusgaita]

This is amazing🔥

[@codeai4178]

I can't thank you enough for these videos sir.

[@deedoi]

Nice and clear explain, thank you so much! :))

[@nicolasrenard2551]

Very good video. More details about standard input would be great.

[@13thravenpurple94]

Great work! Thank you

[@HighReallyWhy]

Thank you >> GREAT TUTORIAL

[@jacekkieblesz655]

Very good explanation ,really very good teacher

[@OscarCedano]

Awesome! Thank u!

[@ugola1]

Amazing!

[@dakhamed]

Thank you so much

[@inestimable7276]

Thank you so so much !!!!

[@udayarpandey3937]

Hello Jay, can you make a series based on real-time project you have worked with? That would be really great. Thank you.

[@SrRunsis]

magnificent videoo!! thxx

[@egysnet]

Although I know most of what you're talking about, I enjoy watching the explanation

[@mohammadmurtazanaiemy7503]

Its useful thank you so much

[@withanaarachchi956]

Many thanks.

[@yazou123]

Thanks a lot

[@devbites77]

Great vid as usual. Any chance of a video on bash special params: $*, $@, $#, $$, $!, $?, $-, $_ And how they are used?

[@evodefense]

thx

[@kwangee]

This topic is seriously useful 👏. I always saw and don't understand 1> 2> in GitHub repo sh file 😂

[@paulojsilva__]

You miss 2>&1 to redirect both output (stdout) and errors (stderr) to same file like find /etc/ -type f > ~/all_results.txt 2>&1

[@surkewrasoul4711]

This man is smart. He knows some physics.

[@nitinnamdev5627]

I am very interested in Linux. while seeing the > /dev/null i am very confusing what is it ? Now i am fully understand . Thank you

[@jyvben1520]

Could do your testing while using a live cd, nothing to break (do not mount the installed system) expect a follow up about what todo with $? in scripts ...

[@gurudayal5743]

as you mentioned about writing a script for sending an email for error or success. How do we do that ,where can I find such script? kindly help

[@kellychristus2496]

Is there any way to catch stdin 0 and place it into a file like stdout 1 and stderr 2?

[@TariqMehmood-1307]

I am your subscriber / fan from Pakistan 🇵🇰

[@louiseantwine3569]

0:38 how do I add a splash screen

[@paulojr1384]

[@jonemiller9603]

Does Linode have training modules ?

[@LearnLinuxTV]

There's some being created right now, some of which by me :) Stay tuned...

[@jonemiller9603]

@@LearnLinuxTV got it. Do you know what other websites have training modules ?

[@GooogleGoglee]

And what if you want to send stout and stderr at the same time to the same file without repeating the file twice in the command line?

[@BigBlueMotors]

See NJUL's comment.

[@themedleb]

find /etc -type f > combined.txt 2>&1

[@krishnapillai6157]

Jai shri ram sir i like your indepth technical skills. 🚩🇮🇳

[@JorgeEscobarMX]

Great video, but why disable dislikes? -- Update: nevermind I see youtube did it.

[@patricknelson]

Yeah it’s really detrimental for people looking for high quality content like this. For example, I can still see dislikes right now (due to gradual rollout), and this video has only 1 dislike with 412 likes.

[@fullstack_journey]

it's because KZbin is run by incompetent fools

[@goodboy8833]

@@fullstack_journey Like u

[@wambamcamcam]

They did it because of the massive amount of dislikes from a Biden speech... Js..

[@marcin2x4]

I noticed that running `find /etc/ -type f 2> /dev/null` still prompts 1 when running `echo $?` As always, awsome content! These tutorials are on my top-list!

[@themistoclesnelson2163]

Comment

[@aleksic1234]

im one of the first

[@MuhammadNadeem-hi1ik]

$ Thanks

[@MaheshKumar-bg5re]

Are you doing meditation? i saw Buddha statue ...

[@AbdulRafay-vi6hz]

Hey, Love your topic but here is an advice for you, Don't get mad, it's up to you to take it. Please don't make you videos like a lecture in a class room, make then light and make it fun for other to learn, Don't be a teacher from year 1890, be cool.

[@AriannaEuryaleMusic]

I actually like Jay the way he is, direct and to the point (No clowning around) plus he is very clear, to me is really fun... Perhaps you might like the arrogance of Luke Smith videos... I don't.

[@AbdulRafay-vi6hz]

@@AriannaEuryaleMusic never heard of Luke Smith... let's see...No you are not getting the point... he's been to formal....I never said that I don't like this content or I didn't understand the point... he's good in explaining but All I am saying is that he should be a little less formal, Read a script in way you are are talking to a person in front of you not like a robot.

[@AriannaEuryaleMusic]

@@AbdulRafay-vi6hz Why "Should he"? You don't have the right to say how Jay "should" run his channel Just because you don't like the format, and you are the one missing the Point, This channel is about LEARNING, if you don't like it, just go somewhere else, there are many Linux channels, and YOU SHOULD be thankful, This Channel is teaching all this stuff for free. I repeat, if you don't like it, don't watch this channel.

[@AbdulRafay-vi6hz]

@@AriannaEuryaleMusic chill out...mad man.... It's social Media and it's my right to give advice it's up to Him to take or not . I'm forcing him... second the advice is for Jay not for you..so buzz off.

[@AriannaEuryaleMusic]

​@@AbdulRafay-vi6hz I repeat, if you don't like it, GTFOH. period.