Shell Scripting Tutorial for Beginners 4 - Pass Arguments to a Bash-Script Video Lecture | Complete Linux Course: Become a Linux Professional - Software Development

hello guys welcome to the next video on
shell scripting to doll for beginners in
the last video we have seen how we can
read parameters in our script now in
this video I am going to show you how we
can pass argument to a bash script so
whenever you start the script you can
pass some argument with it so let's get
started so let's discuss the first way
of passing the argument and how we can
parse those arguments so we will just
write echo and whenever you pass an
argument from our bash script they are
you know stored into a default argument
which are like this so the first you
know argument which you pass in an array
will be stored in dollar one variable
then the second argument which you pass
into you know a bash script will be
saved in dollar two and so on
right so for example if you want to pass
three arguments then it will be stored
in dollar one variable then dollar two
variable and dollar three variables
consecutively right so let's pass some
arguments and let's print those
arguments also so what I'm going to do
is I'm going to take single quote and I
will just write echo dollar one dollar
two and dollar tree okay so let's start
our script and let's see how they are
passed okay so I'm going to start my
script which is hello dot Sh and here
with the script I can pass some
arguments so for example you want to
send some name to a script whenever you
start the script so for example I want
to send three names for example mark Tom
and John for example and I will just
press ENTER and you can see they are
printed so
the first you know name goes into this
variable second name goes into the
second variable and third name goes into
third variable by default right now
where does this name goes so the zeroth
variable whenever for example you write
something like this dollars zero then
you will be able to see this script name
also okay so let's run the script once
again and let's see what happens so the
same script and then with the same
argument press Enter
and you can see the name of your shell
script also comes so this is the zeroth
variables you can say and then the
actual variables which you actually pass
in your script as an argument starts
from variable one and then so on
variable two and variable three okay so
this is how you can pass the argument to
a back script now there is a second way
of parsing the argument whatever you
pass into your script as an array okay
so how we can pass those argument into
an array and then use them so what we
can do is we can declare any variable
name for example odds or arguments
whatever name you want to give here and
then there is a default variable in
which these are you know these argument
goes as an array and to pass death star
a you just need to write bracket and in
double quotes dollar at the rate so this
dollar at the rate you know stores your
argument as in array and to pass them
you just need to declare a variable and
then you know assign those argument
which are stored in this dollar at the
rate into this argument right and now we
can echo those arguments so
just going to copy the psycho command
and then this argh at index for example
one let's print out the argument at
index one and in the last video I've
shown you how to you know print and
re-index right so you write dollar
symbol and then the name of your array
inside the curly brackets so inside the
curly brackets name of the array and
then whatever index you want to see so
for example I want to see index one here
right and then same way you can do with
the second and the third argument at
index two and the third argument and
let's say if you also want to pass the
argument which is at index zero so I'm
going to just write our index 0 okay and
let's run the script once again and
let's see what happens ok so I'm going
to just you know run the same script
with the same arguments and press ENTER
and you can see those argument which we
have passed first so first of all they
are printed using this echo command and
then in the second line they are printed
using this echo command so the important
thing to notice here if whenever you
pass the argument as an array the first
argument which you pass here will be
assigned to the array at index 0 right
so these default variable starts from 0
1 2 3 and 0 is the variable for the
script name right but if you assign them
as an array the 0th index will be for
the first argument right and then first
index will be for the second argument
and the third index second index will be
for the third argument so if you delete
this also then the result will be
the same so let's run the script once
again with the same argument and the
result will be the same right now for
example if you want to print all the
argument at once you can do that also so
you can just write echo and then use
this default variable at the rate which
we have used to convert this argument to
an RA right so if you use echo and then
this dollar symbol and then this default
variable at the rate then all the
arguments will be printed using this
variable so let me comment this code and
now let me print those argument with
this default variable so let's run the
script once again and the result will be
same so all those argument will be saved
inside this default variable okay now
sometimes you want to know the number of
argument which you have passed into the
script so to print the number of
argument which are passed into the
script you can just write echo and there
is a default variable once again which
is hash then it's going to you know
print the number of argument which are
passed so in our case we are passing 3
arguments so it's going to print 3 here
so let's run the script once again and
let's see what's the result so you can
see the result is 3 here okay so this
dollar and the default variable hash is
going to print the number of argument
passed to the bash script okay so these
are some of the ways you can you know
pass the arguments to your bash script I
hope you've enjoyed this video please
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