Shell Scripting Tutorial-58: Know when users log in Final Part 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 58th tutorial
in the series of tutorials on UNIX shell
scripting in this tutorial we are going
to finish our work on the script that
we've been working on for the last two
lessons so I have my editor here and the
first modification that I'm going to
make to the script is on line 28 you see
sleep 60 here and what this does is it
forces the loop to wait for 60 seconds
between iterations right and this is
something we've discussed already but
I'm going to change sixty to one here so
the loop is not going to wait for 60
seconds instead it's going to check
every one second whether the user has
logged in or not right so this in fact
is going to enable us to calculate the
number of minutes as well as the number
of seconds by which the user was late in
logging in right but we will be
interested in determining the number of
minutes only if the value in the time
variable is greater than 60 right so if
the user was 45 seconds late in logging
in then the value for the minute
variable will be zero and since we won't
be displaying that and we actually don't
even have to calculate it right so the
next change that I'm going to make is on
line 23 in fact I'm gonna you know take
out this echo statement completely and
in the if block you know we've checked
already whether the value of time is not
equal to zero but if it is in then we
are going to check whether the value of
time variable is greater than 60 or not
so the test condition is going to be
taller
time - GT that's for greater than 60 and
if this is true then let me type in then
then we can calculate the value for the
minute variable and that's going to be
I'm going to use expr for it and since
expr can be used for integer arithmetic
only if suppose the value of the time
variable is hundred and forty five then
you know if we divide time sorry
daughter time divided by 60 so the
result of this operation is not going to
be two point something instead it's
going to be two right because pxpr
allows us only to perform
you know integer arithmetic operations
and we can also calculate the number of
seconds but for that we are going to use
a different operator the program of
course is going to be exp are but the
expression is going to be different it's
going to be dollar time percent eight
symbols 60 so this is going to give us
the remainder of the division operation
when the value in the time variable is
divided by 60 so if let's say the value
in time variable is 70 then 70 is 10
more than 60 so that will be the value
that will go inside
you know the variable SEC so now that I
have got my two variables I can you know
display them on screen and for that I'm
going to use echo of course and I'll
simply display taller log name was
dollar mi n minutes and dollar SEC
seconds late in logging in okay so
that's there and then I will also have
to put an else block and this block will
get executed if the value of the time
variable is not greater than 60 it's
less than 60 and in this case we won't
be able to calculate the you know value
for the minute variable because it is
zero we know that it is zero right but
the second variable will you know just
have the value that's there in the time
variable right so we can put an echo
statement here as well to display a
message dollar logname was dollar SEC
seconds late in logging in okay and I
have to put fi here to finish my work
and I've saved the script and I'll bring
up my terminal I'll execute it by typing
in SH space check dot Sh when I press
the Enter key asks me for the username
and I'm going to check it when new user
to account
I press the Enter key I get the message
wait and I see that the cursor blink on
the next line
now I'll you know bring up another
terminal window and I'll execute the
command sudo login and I press the Enter
key I'm asked for my password provide my
password and then I have to provide the
user name for the account with which I
wish to login and the user name is new
user - and the password parade I'll
enter and I press the Enter key I get my
prompt and in the previous terminal
window I see the message new user - was
28 seconds late in logging in right so I
hope you guys have understood why we
made the modifications that we made in
the script and you know the first change
that we made was over here you know it
was initially on line 28 but now it's on
line 36 we changed sleep 60 to sleep 1
and that allowed us to calculate the
value for the minute variable and the
second variable so basically we had the
time but you know we weren't able to you
know determine the number of seconds but
you know this change here allowed us to
do that so you know I hope you guys had
fun watching this tutorial in the next
tutorial we will discuss something
interesting again so see you then and
thank you so much for watching this one
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