Shell Scripting Tutorial-21: Reverse Quotes Or Accent Graves Video Lecture | Shell Scripting: Discovering to Automate Command-Line Tasks - Back-End Programming

hello guys my name is mother and welcome
to my channel this is the twenty first
tutorial in the series of tutorials on
UNIX shell scripting now in this
tutorial we're going to prepare another
shell script but before doing that I am
going to demonstrate something to you
using the terminal what I'm going to do
is I'm going to use the cat command and
prepare a text file I'll call it test
and I'll just type in some text in it
like my neighbor's dog is annoying .
save my document by pressing ctrl d like
an LS and see that my test file is right
there in the home folder
now in the previous tutorial we change
the permissions of SS 1 not SH we made
an executable program and you can see
that the shell is highlighting SS 1 dot
s agent green ink which means that it's
an executable program and that's a you
know unlike the other names that are
being displayed in the output of LS so
that's it and let me clear the terminal
for you now what I want to do is I wish
to set my positional parameters by
extracting the output from my test file
and by that I mean I want daughter 1 to
have the value my daughter 2 to have the
value neighbor's daughter 3 to have the
value dog and so on and so forth now I
can't do this by typing in said cat test
although you know some of you might be
wondering okay what's wrong with this
command because cat test is basically
going to generate the output of test and
that should set the positional
parameters but how would the shell know
that I wish to execute this part of the
program as a command first and then
assign the output of that to the
positional parameters that set holes so
the thing that's going to help the shell
acknowledge that is called action grave
or reverse code and they all they always
come in pair
and you can find them on the left side
of the key one on your keyboard and you
when you press it once it gets there you
don't have to press the shift key to get
it and the shift key would get you the
tilde and that we don't want so when I
execute this command when I press the
Enter key and then when I see my
positional parameters by executing
dollar star I see that my positional
parameters have been set with the output
from the test command so sorry not the
command but the file test so that was it
and now we're going to prepare a shell
script and it's again going to use
positional parameters we are going to
save this file first and we are going to
call it SS six this is the sixth script
file that we've prepared I'm going to
save it in the home directory and what
this file is going to do is it's going
to rename a file from my home directory
to the file name and then it will have
an extension of the user login name
which is myname currently so let me
first show you guys something when I
execute the command Who am I
it's a command that we learned in the
very beginning of the course and when I
press the Enter key
I see that the first field is my name
that is my login name the second for you
is my terminal ID and the third field is
the time and date at which I logged in
so if I would set my positional
parameters with the output of Who am I
then dollar one will hold the value
motherhood or two will hold the value of
my terminal ID and dollar three will
hold the value of the day and time at
which I log 10 right so now in my script
file let me first put a comment like
the script renames a file to file dark
name where name is the login name of the
user executing the script that's it
that's comprehensive enough and what I'm
going to do now is I'm going to first
use a variable name and I'm going to
assign it the value of the file name
that's going to be passed through the
program as an argument right so when I
pass in the name of my file suppose if I
execute this program with test as an
argument then test will be stored in
name so that I can use dollar one again
for storing something else and then I'm
going to execute set and in the action
graves I'm going to put in Who am I
so basically what I am going to do now
is I'm going to override the previous
value of dollar one by my login name
which is mother and in the next line I'm
going to execute MV because we have to
rename our file so then would be dollar
name space dollar name thought dollar
one dollar one in this case would have
my name right I'll save this file
it's taken some time sorry about that
okay it's done now I'll clear my
terminal first I'll run LS to show that
I have my final test in here and soon it
will be renamed with test dot mother you
will see how SH space SS six-star SH and
then test will go as an argument and I
press the Enter key and when I now run
LS I see that my file test is called
that start button so again a quick recap
of the program what we did is we first
copied the value of the argument that we
pass through the program in a variable
called name so that we can use dollar
one for other purposes and in the very
next statement we set the positional
parameter dollar one with the output of
who am i and we've included who am i in
the action rates because we want Who am
I to be executed as a command before
setting the positional parameters and
then in the last statement we've used
the MV command to rename our file from
dollar name to Torah name dot the user
login name so test has been renamed to
test dot mother so there you go that was
a sixth script file in the next tutorial
we're going to learn something
interesting again thank you so much for
watching this one and please subscribe
to my channel