Linux Command: 'tee' - Watch & Log Command Output

The 'tee' command allows you to monitor a command's output in your shell (or piping that output to another program) while *also* writing it to a logfile. Now you can have your Linux cake and eat it, too!

[tobara]

You might have wanted to mention the magic of "2>&1 " before piping because without this it only pipes the STDOUT but with this it pipes STDOUT and STDERR. Considering the most common use-cases, this is probably a must-know.

[MFM]

Perfect explanation of "tee" to a tee!

[kylabutler]

Thank you so You explained this better to me than ANY other person or course! Thank you!!!!

[DanielSMatthews]

alias tea='tee -a'

Unless you have the test editor "tea" installed. :-)

[sysghost]

Another tip on this command:
Good to redirect the output to a process run as another user.

Simple example when logged in as a normal user:
This will not work: sudo echo "myawesomecomputername" > /etc/hostname
This do work: echo "myawesomecomputername" | sudo tee /etc/hostname

Sure there are many other ways to to this particular example. The point being is that one sometimes need to run something as a user, but need to process the output as another user. tee will help there.

[OddRandomThoughts]

cool, this would be great for something like sudo watch tail -f /var/log/syslog | tee -a bla.txt if you wanted to capture just the output of a specific configuration change or problem for reviewing later. Thanks for the great tip!

[gaithalbadarin]

nice, Unix/ Linux every day something new to learn.

[JustinC]

Neat little video. Now I will use tee. Thanks.

Man, all these videos are super useful, and great quality. Especially love the series on Python 3.
Thanks a lot.

[fifothebot]

Another nice use case is when you want to log an interactive command, so something where you get asked stuff once in a while (username or password for example). Even though the script command might be more useful in that scenario.

[OddBallTrails]

Your videos deserve my subscription, thanks.

[SamSharifian]

Hey, thanks for the cool tutorial... but can you also explain what are those green/red arrows on the left side of your prompt?!
What terminal are you using? Isn't it GNOME's "terminator" by any chance?

[QuestionTheTruth]

So, I have a raspberry pi, and on it it's only been command lines running, I now noticed that I have a full log somewhere with every commands used since like 2 years back, but I can only see one at a time, I want to be able to ... download a file which i can skim through to find what commands I used back then, because I don't remember, I have my bots on it, and that's it basically. "/

[Steeldragon]

Thanks for a video, though it looks more like one of the "Hello world" one...
Would love to see the use of this command along with some python/bash script, to actually show it's usefulness and convince me to use it. We need more high level stuff! :) Still thanks ;-)

[modern__ninja]

Awesome! more video like this please :3

[zapy]

An interesting feature would also be to save the command itself.

[baleia]

I`m a newbie in Linux, but for this purpose of writing the output to a file I could just use nohup right!?

[micmac]

Thus I can write to multiple files like: date | tee f1 | tee f2 | tee f3 > f4

[AnonymousAccount]

ooph....popping those P's almost broke my speakers....do you have a governor on your mic

[danydanger]

For whole shell output to a file Try using script command, use like this --> script /home/user/myWork.out now whatever u do will be logged in this file, press "ctrl+c" to exit from this script output and come back to your Shell !!!!

[JohnnieWalkerGreen]

how to tee 'tail -f /var/log/kern.log | grep XXX' ?