Linux Command Line Tutorial For Beginners 5 - I/O Redirection Video Lecture | Complete Linux Course: Become a Linux Professional - Software Development

look guys welcome to the next video on
Linux command line tutorial for
beginners in this video I'm going to
show you how we can use redirection in
Linux first of all what is redirection
redirection simply means capturing
output from a file command or program
and sending it as an input to another
file command or program and let's see
what are the options we have for the
redirection so for example you want to
you know transfer some things some
output so I will just write output here
and then you want to redirect it to a
file for example so in this case we want
to send some output to a file and the
Poynting you know end of this arrow is
the direction of your output so you want
to send the output to the file so this
point means the direction of your output
right so let's see how we can use it so
in the last video I've shown you how we
can use the cat command in Linux so we
are going to use this cat command to
create a file and then transferring our
you know stream to this file so just
right cat here and then this angle
bracket this means we want to redirect
our you know input or whatever output we
are going to type in the terminal to a
file and let's name a file something so
for example text dot txt ok and when I
press ENTER here you will see there is a
new file created right as soon as you
press Enter now whatever you write here
then this content will be written to the
file for example I will just write line
1 line 2 line 3 for example and this
will be written to your file and to you
know show the end of the file you just
need to
press ctrl + D so just press ctrl D to
you know indicate that this is the end
of your pile and then you are out of
this cat command and let's see what's
the content of this test file so I can
just cat this test file here so just
press ENTER and you can see the content
of this test dot txt file right now for
example what I want to do is I want to
once again transfer something else to
this file so once again I will just do
cat with this angle bracket and then the
file name and then this time I want to
add for example line 4 here and then
line 5 for example and let's say I want
to add one more line for example line 6
here ok and then I will just cut press
ctrl D - and this file and now I want to
see the content of this file so I will
just give cat dot a test dot txt right
and press ENTER and now you will see
that this test dot txt file contains
line four five and six and earlier
whatever content we have written to the
file is overwritten by the new content
right this content now for example you
want to append to the file you want that
this file should not be overwritten but
it should be whatever you want to add to
a file it will be added from the next
line for example right so what we do in
that case we give the same command with
two angle brackets so this is for
appending to the existing content of a
file right so when you give two angle
brackets and press Enter and now I will
say line seven here line eight and
line 9 for example okay and I will press
control-d and then once again I will see
the content of the file and now it shows
me line 3 4 5 witches from my last you
know come on and then I have added these
three new lines so if you want to append
to the existing content of a file you
may want to use these 2 angle brackets
okay
now sometimes you want to you know add
two files and then transfer the content
to the new file right so I have these
two files list one and list two for
example so let me show you the content
of these two file first I will clear the
terminal it should be tinea and press
ENTER and then cat list one for example
it contains these three lines and let me
show you the content of this two also so
it contains these three lines also right
now I want to add the content of these
two files and transfer it to a new file
so what I can do is I can just write cat
and then I will just write the name of
these two files list one and then space
list two and then I will give the angle
bracket here
something like this and then I want to
transfer the content to a new file for
example let's say its name is out dot
txt something like this okay and let me
make it a little bit bigger so we can
see the command so this is the command
so I want to join these two files and
then transfer the content of the
concatenation of these two files to our
new file so when I press ENTER the new
file will be created this file already
exists here so it's not creating but if
it doesn't exit it will create this file
and then when I see the content of this
out dot txt file
I can see the combination of our two
files so in this way you can add any
number of file for example you have
three or four files you can just write
list one list two list reenlist for and
then redirected to a new file
now for example I would just want to
redirect the content of these two file
to the file to itself so what should I
do
I can just write something like this so
I just write cat list one list two and I
want to transfer the output to the list
to itself so I will just write here list
two and press Enter and it says input
file is output file here right so you
cannot do this like this so what you
need to do here you need to do something
like this so you just need to give the
list 1 dot txt and then append it to the
second file which is our list 2 dot txt
file right instead of giving this
command if you give this command this
will work so when you press enter this
command is executed and let's see the
content of list 2 now so just write list
2 dot txt and press Enter and now you
can see less to contain the combination
of these two files right so in this way
you can use a redirection in Linux so
it's not you know particularly related
to the cat command you can do the same
thing with for example I will just write
LS minus L to out dot txt so I will just
write out dot txt and press Enter and
when I see the content of outdoor text
then you give me the output of LS
command right so it's not particularly
related to cat command you can use this
redirection to any other command with
any and other come on for example LS or
CD or any other command or program right
so I hope you enjoyed this video please
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tribe and bye for now