Linux Sysadmin Basics 04 -- Shell Features -- Pipes and Redirection
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- Опубліковано 14 бер 2014
- Learn how to use two of the most powerful concepts of the Linux shell: Input/Output Redirection and Pipes.
Input/Output redirection enables processes/commands to take input from files, the network, or other places (and receive input from the same).
Pipes allow you to wire together different commands to create your own custom super-commands.
In this video, I'll cover both UNIX features, using basic bash (Bourne Again Shell) in Linux.
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Pipes and redirection? More like "Against ignorance, your videos offer protection!" Thanks again for sharing such a great series.
Excellent explanation of the concepts of STDIN, STDOUT and STDERR !
Dude!!! A bunch of lights are starting to light up in my head!!! My girlfriend doesn't like you as much as I do (i spend more time listening to your tutorials than I do with her!!LOL) But I find your Tutorials are more than informative, my College Prof and his notes are very confusing... I have a second Mid-Term next week, and I will be going through all of your Videos to Help me. You are now my new best friend!! Thanks Dave
Hey man, glad to hear that these tutorials are working for you. I've got a bunch more coming very soon. Stay motivated, do cool learning projects, and have fun!
did u pass your Mid-Terms? :)
@@drakemarker asking the real questions
This guy... making me love Linux and him self at the same time - ,,ou my lord, I'm truly sorry for that" :DD. Bro U R a Gem on YT!
OMG thank you so much. I have searched all of youtube for a good playlist on Linux and finally!! I'm a huge Linux enthusiast and this is my jam...again, thank you very much!!! Love from India
"oh my lord...i'm truly sorry for that" :D
you're tthe best!
This is my first comment on youtube ever and it well deserved for your easy to understand guide on linux, if this was ebay id be giving you ++++ top seller, cheers you really have helped me.
Thanks; much appreciated!
These videos are great. The best I have found so far. Your style is very matter of fact. Thanks so much for making them. Keep up the great work!
Just started on your videos to build up my Linux knowledge. Currently a Windows sysadmin with quite a bit of powershell experience and finding quite a lot of the concepts similar. Thanks for the effort.
ps aux | cowsay | lolcat
this is the best thing i ever done...
Made my day!
read a pocket guide and couldn't understand anything you explain these concepts really well man! Thank you so much for this
Love your explanations! you truly make things really easy to understand!
Thank you
These are really well done. I needed a refresh, and more. I have both, including some things I had not known were advanced... Thank You. I am reviewing the entire series.
Two videos by this guy & I think I can pretty much apply for sysadmin work.
Hello David, I just want to say thank you for this great course! I like your style and explanations a lot, so I bought your Udemy course as well. Keep the great vids coming! ;) Cheers, Anna from Hungary
Hey, thanks for the kind words; much appreciated! I hope you have a blast with the Udemy course.
Video is structured in very easy to understand manner
Excellent explanations my good sir!
This series is useful and fun. Thanks, man!
Thanks a lot for your videos. They are amazing! So much effort into them.
Appreciate it! It's all worth it; I get 5-10 emails a week from people who have gone through and ended up getting into Linux/DevOps/Software Dev positions and used this playlist to get started. Keep learning and practicing and there is no limit to the payoff.
Great! I love this course.
thanks for these videos. Really helps a self taught person like myself build the foundations to be confident working in linux.
lol 4:33 ...mac guys thank you for the videos way better than my udemy course I bought.
your videos make me to install a vps somewhere in Indonesia because my mac,isn't mine and my brother will kill me if i install something like vmware in his machine. thanks man i learn a lot from you,you udemy project is my next check in my agenda
Since I came from Windows, I hadn't found file extensions particularly useful. But since using Linux with a terminal, I've found file extensions to be almost necessary. I now almost always name files with an extension. It's just much more user friendly, as it does away with ambiguity. File extensions are particularly useful when using ls with the -X flag: this sortes files by extension alphabetically.
you can also define custom file types with the magic command
Thank you for these videos!
Damn. Thanks so much. Just a beginner out there. Had been using "" | grep 'sth' "" but never knew anything about piping. Just thought it was some strange command but now it makes so much sense. Words cannot explain how much thankful and amazed I am now.
Awesome video bro!
Great video. Thank you for your work!
Thank you for explaining this!
Wow, excellent video!
This is very useful. Thank you very much.
Thank you, easy to follow
Good work. Helpful.
thanks so much for the explanation!
Great video.
learning from this in 2023
Great examples
Loved it. Thanks.
Great tutorials and I'm loving it. Just a few suggestions though. Firstly, if you could use built-in colour schemes for a terminal, it would be easier for learners/beginners to distinguish file types vs commands etc. I know Linux veterans love to use green on black. Secondly, if you could increase the font size which makes it more clearer to read.
Thank you very much for putting these videos up. I feel like this subject should have been covered much later in the course as it is not immediately useful like the things you teach before or after it.
awesome, best Linux tutorial I have seen so far
Thank you.. Spot on man. Very good
OH MAH LAWD... Nice explanation. :D
Thanks for the video!!, really useful. I would use Ctrl + l more often so that we can see the terminal more clearly, constructive suggestion :)
you are the best.. seriously you are
thank you so much for these videos, now i tried to output the results of a ping to a text file
hahaha i lost it when he said there will also be a typing class later hahaha. but actually tho, as someone who's used linux for years, this is a great course for those who want to hone their skills and take it one step further
Thanks Dave
thank you for not giving me motion sickness
Thanks :) after 6 years)
excellent thanks sir
Lol, so I ran "sudo apt-get mailutils", then ran your example command of "mail -s "subject" user < test.txt" and I don't know how to check it. Always fun being super noob. I now have an email that tells me "You're a huge dork" floating around somewhere for me to stumble on some day when I know how to check it.
i hope you are a linux professional now.
If you type 'mail' into your command line prompt and press enter it should display the message you sent to yourself.
You making six figures yet?
Love these videos, Thank you so much for taking the time to share this information. Curious about the "black square" that shows up once in a while...:)
Me too
I know I might be a little late, but the black square appears whenever he moves his mouse then starts typing in the terminal. My guess would be that his cursor disappears, and his recording software doesn't know how to handle it, freaks out, and fills the bounding box that it puts around the cursor in completely black.
Man, I love you
Thank you so much!!!!!!!
Thanks again
Yo... Less is more :D Awesome stuff very well explained thanks alot
Hey, Great Video's Do you offer them as a download at all? Am going away next weekend and will have no internet, I would love to spend time learning abit more linux.
Try this (without quotes): "sudo apt-get install cowsay && sudo apt-get install fortune && sudo apt-get update". After installing the programs fortune and cowsay using the command above, do this: "fortune | cowsay". Do you see what happened? If not, try again. And again. Try fortune without cowsay. Now do you see? cowsay takes its arguments and prints them with a cow. fortune picks a pseudo random quote from a list. Pipe them together and you have something amazing.
This is hilarious! Thanks a lot for the tip! This way you don't need the internet to waste time :D
_________________________________________
/ Once there was a little nerd who loved \
| to read your mail, And then yank back |
| the i-access times to get hackers off |
| his tail, And once as he finished |
| reading from the secretary's spool, He |
| wrote a rude rejection to her boyfriend |
| (how uncool!) And this as delivermail |
| did work and he ran his backfstat, He |
| heard an awful crackling like rat |
| fritters in hot fat, And hard errors |
| brought the system down 'fore he could |
| even shout! |
| |
| And the bio bug'll bring yours down |
| too, ef you don't watch out! And once |
| they was a little flake who'd prowl |
| through the uulog, And when he went to |
| his blit that night to play at being |
| god, The ops all heard him holler, and |
| they to the console dashed, But when |
| they did a ps -ut they found the system |
| crashed! Oh, the wizards adb'd the |
| dumps and did the system trace, And |
| worked on the file system 'til the disk |
| head was hot paste, But all they ever |
| found was this: "panic: never doubt", |
| |
| And the bio bug'll crash your box too, |
| ef you don't watch out! When the day is |
| done and the moon comes out, And you |
| hear the printer whining and the rk's |
| seems to count, When the other desks |
| are empty and their terminals glassy |
| grey, And the load is only 1.6 and you |
| wonder if it'll stay, You must mind the |
| file protections and not snoop around, |
| |
| Or the bio bug'll getcha and bring the |
\ system down! /
----------------------------------------------------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||------------w |
|| ||
(It looks a lot better in the terminal, had to adjust the spacing when pasting it here.)
Some other packages I found while messing around with fortunes and cowsay:
fortunes-off (quotes and text that apparently may be offensive to some - the one below is one of them)
xcowsay (graphical cow floating outside the terminal on screen!! :D)
____________________________________________
/ There was a young girl of Darjeeling \
| Who could dance with such exquisite feeling |
| There was never a sound For miles around |
| Save of fly-buttons |
\ hitting the ceiling. /
----------------------------------------------------------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||--------w |
|| ||
nice video
Thanks!
Forgot to mention 2>&1 and &>. Redirect stderr (file descriptor 2) to stdout (file descriptor 1), combining error messages with normal output into a single stream.
Hi Dave! Excellent linux course! I have a small question regarding namedpipes; I've created 2 pipes with command: "mkfifo p1 p2"; tried to redirect the containment of a file in p1 with: "cat file1.txt > p1" and in another shell trying to see the result with: "cat < p2", but nothing happens...What can be the cause? I'm in the same path in both terminals. Thank you!
Thanks so much Dave!! Amazing course! Do you have any suggestion on which shell might be good for a beginner? I saw that in some later videos you cover bash-scripting. You think it's better to stick with bash or does fish also work (maybe even better;)?
Sticking with bash is your best bet for a tech career, IMO. Fish is great for personal use but it's unlikely that you'll get buy-in from the entire engineering department to install, support, and standardize on it across a few hundred (or thousand) servers. Also it *encourages* scripting in shell, which I'm more and more wary of as I get older.
If your bash script starts using a bunch of logic, string comparisons, error handling, arrays, that's a strong signal that it would be better in a 'real' programming language (usually whatever your company has standardized on -- python, go, etc.).
wow, thank a lot for the extensive answer:)!! I'll stick with bash;) Although I don't know if I ever manage to write some real bash-script... Thanks so much for these outstanding classes! Especially these days it super helps!
THANKS HOMIE
I see what you did there with "echo < grep-example" at 11:43, for anyone interested it doesn't work as one might expect because "echo" reads from its arguments, not STDIN, they are not the same thing, even though some programs can read from both (like, "cat")
whaooo...this is life made easy.....
Deffs buying this course. There will be a typing course later... just kidding
thnk u
Great video! when sending file > new file I get: permission denied
do I need to chmod this file to move it? sole user =)
Thanks in advance , very informative. Im a Slacker. /slack 14.0
thx for the entire serias, i have 2 questions:
1.i couldnt understand the mail sending, where im writing the message body?
the adress for whome im sending to?
2.when u exlaind the pipes thing, i couldnt understand what is aux?
thx again!
Good questions! The 'aux' in 'ps aux' is a few options that I like to use with the 'ps' command. It's the same as writing 'ps -a -u -x'. Check 'man ps' to find out what each option does.
Regarding mail sending, the concept of *input redirection* means that you're grabbing the input for the command from the other side of that 'arrow.' In this case, a text file. Google 'input redirection linux' for a more detailed description.
12:08 I wrote 1< and it waiting for my response but its not going through like a loop. that does it mean.?
What is the black box that keeps moving arround and occasionally covers txt.
bahaha at the beginning of the video i thought this was a sarcastic comment about the cursor... as I kept watching, i said to myself, "WHAT THE HECK IS THAT BLACK BOX THAT COVERS UP RANDOM PLACES AND GETS IN THE WAY" 😂
Let's say I want to sort by "COMMAND" or "CPU". not for any real reason, but for syntax purposes. can you explain how I would accomplish this. I am getting different answers from google search and have not found a response that works.
Does 1> also appends or overrides?
Rip open a shell and try it!
cd /tmp
ls -alh 1> foolog
cat foolog
ls -alh 1> foolog
Post the answer here so others can benefit :-D
That less command is great. I've always got mad if I CAT a file and it was too long and couldn't scroll (even though you sort of can in terminal) then I had to use nano. but this is helpful.. Now I can just
cat longtextfile.txt | less
:)
+Tino Suteu Now I'm paranoid that I did cat | less in the video...the 'cat' command is generally just for concatenating files (gluing several files together). If you just want to look through a single file, `less | filename` is enough. Although it's not like kittens will die if you do cat | less :-).
thanks for the video, but whats up with that black pixels during some spots, 2:01 for example,
+Dean suphanthamit Annoying problem with my screen recording software and the default linux cursor, sorry!
hello Mr how can i imput arrow keys on a scrip program? i'm making a game and have to input some instructions with out using enter for each command... any help?? pliz
Hey, I've never done that but I started googling around:
stackoverflow.com/questions/1805840/arrow-key-via-stdin
Great videos but how do I find out how many videos are in this series. How do add them all to my playlist?
There's a link in the description to the full playlist? ua-cam.com/play/PLtK75qxsQaMLZSo7KL-PmiRarU7hrpnwK.html
Thanks mate. I realised that afterwards. Your's is the exception. Many other series dont have such links.
what are these black squares?
9:45
I didn't quite get few things:
Does 1> append or rewrites?
Does 2> rewrites the file? If that's the case - how to append an error and not rewrite the whole file?
Okay, 1> rewrites.
Okay.2, 2> rewrites, 2>> appends
What's that annoing black rect crawling on the terminal and covering letters?
Edit: OK it is probably some bug with the cursor on the VM.
+Strategiusz Exactly right -- sorry about that!
I just have a couple questions so I'm totally clear on this:
Are STDIN, STDOUT, and STDERR always equal to 0, 1, and 2?
Or when you put
echo "STDIN --> 0"
is that kind of like assigning STDIN to 0?
I think my first question is the right answer but i want some clarification on that..
+Jacob Jacobucci Those echo statements were just to illustrate the file descriptors and what they are. They're actually defined as 'devices' in /dev:
$ ls -alh /dev | grep -i std
lrwxrwxrwx 1 root root 15 Apr 19 23:30 stderr -> /proc/self/fd/2
lrwxrwxrwx 1 root root 15 Apr 19 23:30 stdin -> /proc/self/fd/0
lrwxrwxrwx 1 root root 15 Apr 19 23:30 stdout -> /proc/self/fd/1
You can see that when searching for all files in /dev that contain the string 'std'', these three file descriptors are found. They are actually links (shown by the 'l' character at the beginning of the permissions bits) which point to the file descriptors in /proc.
This is where the actual "assignment" is taking place (the link basically assigns the name to the file descriptor in the /proc virtual filesystem, which is essentially a fake filesystem that lets you interact with the Linux kernel). If you really wanted to mess with someone, you could change these, although I don't really recommend it :-D. Sort of like doing "True = False" in a programming language...you should expect someone to dedicate their life to finding and physically harming you if you do this in production.
+tutoriaLinux Haha ok cool, that make a lot more sense. Thanks for the response. Also really enjoyed watching the linux basics course videos. They really helped me as a beginner and if you are going to make more videos I look forward to seeing them!
You started going too fast there and my brain exploded.
Sorry to hear it! Where did I lose you?
I did not understand "pipe |", rest everything was perfect. Thanks!!
1st commands output is given as input to 2nd command
@@silverzero9524 I understand that but what is the significance of ps aux | less ????
@@beagleonvodka Did you see the difference between ps aux and ps aux | less ? You will notice that the second one allows you to scroll through the output of ps aux with your keyboard up/down arrows, for example.
@@epochseven4197 Thanks
Bwahahahah 3:31 typing course :D
Hey!...Can u pls tell me hw to redirect the output of "ls -l" into an excel with data in each field of excel...
I know this is an old comment but you cant do that bud, excel is ms.
Linux User Hahah, that was a funny question to ask, but actually YOU CAN, not directly of course. If you turn ls -l output into a utf-8 comma-separated text, then you can later import that file into MS Office so that each comma-separated value is in a different field, just like he wanted. It's all my strictly theoretical thinking right now. But I still keep asking myself if maybe the guy was just trolling)))
What's the difference between ps aux | less and ps aux > less ?
The first paginates the output of ps aux (via less) while the second outputs the ps aux into a text file named "less".
Suhweeeet
is it posible to remove that black box!! annoying!
this is where it started getting a bit of above ....
6 Winblows users disliked this.
Bookmark 11:06
the black square is driving me crazy
It might be a good idea to mention, that this stuff is NOT specific to Linux. It works on all POSIX-compliant OSs.
I used to spend a lot of time pointing out details like that but over time all the 'stop rambling' comments have conditioned me not to. Thanks for pointing it out, though :-D
you sound a lot like jim halpert hahaha
I didn't understand :(
"this should be in a fail"
dwm.suckless.org/
Not sure if you know about this Window Manager, but I think you should take a look :)
It's less bloated than i3.
Anyone else seeing a random black square in every video