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Learn to route command output to two locations at the Linux command line.
Videos can also be accessed from the Linux Essentials Playlist on YouTube.
Linux tee Command Summary with Examples (3:46)
Our ninety-first word, or command to memorize is
tee from our category
tee allows you to route to both
standard output and a file.
||Print help screen|
||Append to file instead of overwrite|
Recall from videos (tutorials) #87 to #90, we're building a
script to demonstrate workflow, well now we'll cover the
tee command and
add it to a script.
Before we start, it helps to think of commands as mini programs and
most follow this structure:
command -option(s) argument(s).
tee command has
4 options and the argument is a filename followed by
a second pipe. Think of it as if the second pipe can be for additional
processing by another command. And we'll see that in a second.
Like most commands, help is available with double-dash
-a appends, rather than overwrites
output to a file.
So why is
tee an important command?
Well, we can eliminate the need to write two separate commands to
route output to two different places.
And now you know how to do that.
Okay, the best way to embed this in your memory is by typing in your own terminal window.
Find this on your Mac using a program called Terminal. On Linux use Terminal or Konsole, and currently Microsoft is adding this functionality to Windows.
Here we go. Let's
ls all of the
text files in our working directory.
And there are quite a few. You could pipe, or redirect this output to
another command, like the word count for lines using
And get 42 files. So you've routed to another command.
Next, what if you wanted to stop after the first listing, write to a file, and then keep processing with another command? Hmmm.
So let's do it in our script, at the
bin directory we have a script. It's
(Below is the screen from within
(Here we added lines about video 91 and below.)
Here I added a comment, text to explain the output, followed by the
ls *.txt from earlier, and then
tee it to a file, and then report out
the last 5 lines.
Okay, please pause if you'd like to catch up on your end and then we'll try it out.
Ctrl-x to leave
y to confirm saving.)
And last, explicitly run with this, in the
bin directory, then
And there's our output. As you can see, the explanation, it wrote to the file and gave us the last 5 lines. Very good.
Okay now you know how to use
And you know the syntax for commands, options and arguments.
One last tip about the
command. So the append option
especially helpful if you're interested in specific entries to logs,
Okay, thanks for visiting today. I hope this was a helpful
introduction to the
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