Shell Scripting Tutorial for Beginners 8 - Logical 'AND' Operator Video Lecture | Complete Linux Course: Become a Linux Professional - Software Development

hey guys welcome to the next video on
shell scripting tool for beginners in
this video we will learn how to use end
operator with a statement so let's get
started so suppose we have a student and
we need to evaluate his age and we need
to evaluate the age in such a way that
his age should be greater than 18 and
less than 30 years so how do we do it so
let's say we have a student whose age is
25 right and then we will write an if
statement so I'm going to write a if
statement and then as we do with if
statement we will just write the
condition so we can write here age so
dollar age and then we can say if age is
greater than gt4 that with minor right
so greater than 18 and we need to write
the second condition also so for that we
can use and operator and there are two
ways of using app and operator with if
statement in bash script one is to use
these kind of four double and symbols
and then make a second square bracket
and then give our second condition here
so the second condition is dollar age if
the age is less than minus L T less than
thirty right so we are evaluating two
conditions here if the age is the
greater than eighteen and the age is
less than thirty then and then we will
say success or fail so we will just echo
valid age otherwise we will echo so let
me write L and then we
eko age not valid right and then we will
end the eight condition by FY so
whenever you want to evaluate more than
one condition you can use two kinds of
operators one is and operator and other
is all operator
which will be we will see in the next
video right so in this case we want to
check whether the age is greater than 18
and if it's less than 30 at the same
time so we use end operators and if you
know little bit of programming you
already know that and is for checking or
validating both of the condition so if
and only if both the conditions are true
then only this code will be executed
otherwise this code will be executed
right so let me run the script so I'm
going to go to my desktop folder so CD
desktop and then I'm going to run my
script and you can see age not valid
right and why it's not valid because I
think I forgot this space between 30 and
the ending square bracket so we will run
our script once again and this time it
fails valid so always remember to give
the space here and here okay so now
let's give the age which is out of the
range for example 50 year and let's see
what happens so I'm going to run the
script I'd say is age not valid and
what's happening here the first
condition is true because the age is
greater than 18 so this condition is
true but the other condition is false
the age is not less than 30 right
therefore the whole condition is false
right in order to pass this and
operators you need to pass both the
condition this condition and this
condition also right now
there is a second way of using and
operator and this way maybe is for some
people it can be easier because it only
requires one square bracket and not two
square brackets so what we need to do is
we can just remove these square bracket
from here and then we can use a - a flag
which stands for and okay so if you want
to just use one square bracket then for
an operator use - a flag and the
condition or situation will be the same
so - a stands for and operator and let's
run the code once again and it's a age
not valid and let's give the valid age
and once again the age is valid now
there is one last alternate way of using
and operator with your if statement and
that is you can use these double and
operators like this but you need to use
the double square brackets like this for
that okay so if you want to use double
square back brackets
also you can use this kind of operator
and it will also work fine so let's run
the script once again it saves each
valid and let's give the invalid age and
let's run the script once again it says
age not valid so there are three ways of
using and operator one is this wave with
two brackets and this and operator if
you want to use one bracket then you
need to use - a here and if you want to
use two brackets then you can just give
two conditions separately in two square
brackets so in this way you can use end
operators with if statement in scripting
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