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Shell Scripting Tutorial for Beginners 3 - Read User Input Video Lecture | Complete Linux Course: Become a Linux Professional - Software Development
FAQs on Shell Scripting Tutorial for Beginners 3 - Read User Input Video Lecture - Complete Linux Course: Become a Linux Professional - Software Development
| 1. What is shell scripting and why is it useful for beginners? |  |
Ans. Shell scripting is a way to automate tasks by writing scripts in a shell programming language, such as Bash. It allows beginners to create programs that can execute commands, perform calculations, and handle file operations. Shell scripting is useful for beginners as it provides a simple and powerful way to automate repetitive tasks and manage system configurations.
| 2. How can I read user input in a shell script? | |
Ans. You can read user input in a shell script using the "read" command. This command prompts the user to enter input and stores it in a variable. For example, you can use the following syntax to read user input:
```
read variable_name
```
The user's input will be stored in the variable_name variable, which you can then use in your script.
| 3. Can I provide default values for user input in a shell script? | |
Ans. Yes, you can provide default values for user input in a shell script. By using the "read" command with the "-p" option, you can specify a prompt message that includes the default value. If the user does not enter any input, the default value will be used. For example:
```
read -p "Enter your name [John]: " name
```
In this case, if the user does not enter any input, the variable "name" will be set to "John" as the default value.
| 4. How can I validate user input in a shell script? | |
Ans. You can validate user input in a shell script by using conditional statements and loops. For example, you can use the "if" statement to check if the input meets certain criteria, and prompt the user to enter valid input if it doesn't. Additionally, you can use regular expressions to validate input patterns, such as checking if a user entered a valid email address or a number. By combining these techniques, you can ensure that the user input is valid and handle any errors gracefully.
| 5. Are there any best practices to follow when writing shell scripts? | |
Ans. Yes, there are several best practices to follow when writing shell scripts. Some of them include:
- Use meaningful variable and function names to make the code more readable.
- Comment your code to explain its purpose and any complex logic.
- Handle errors and edge cases properly by using conditional statements and error handling techniques.
- Use indentation and proper formatting to improve code readability.
- Avoid using unnecessary commands or redundant code to make your script more efficient.
- Test your script thoroughly before deploying it to ensure it works as expected.
By following these best practices, you can write clean, maintainable, and reliable shell scripts.
Text Transcript from Video
and the guys welcome to the next video
on shell scripting tutorial for
beginners in this video I'm going to
show you how you can read inputs from
your terminal in your script so to get
input from the keyboard you use read
command the read command takes input
from the keyboard and assigns it to a
variable so let's see how we can use it
so for example I want to allow the user
to enter some names so I will just write
for example first of all echo and then I
will just print some text for example
enter names or name right and then I
want to allow the user to enter the name
so for that I can use a command called
read and then whatever variable name I
right after this read command your input
will be saved in this variable okay so
for example I write the variable name
name then your input will be saved
inside this named variable now I want to
print this variable so I can just write
echo and then I can just write entered
name and then the variable so use dollar
symbol and the variable name as we have
seen in the last video so let's run the
script and let's see what happens so it
asks me for entering the name and I'll
enter some name for example Max and then
press ENTER and then it says entered
name is max which is totally fine right
so whenever you want to take an input
from the terminal use read command now
for example you want to enter multiple
variables in the same read command you
can just do that also so for example I
want a user to enter multiple name so I
will just edit this text to enter names
and then instead of using one variable
I can use for example name one and then
space name to let me just correct name
two and then space name three and so on
right so whenever you want the user to
input multiple variables just write the
variable and then separate it by the
space another variable separated by the
space and then another variable and to
print these names you can just print it
like you do normally for example names
and then first name is name one and then
comma for example and then once again
name - and then comma and then print
them variable name three okay
so let's save the code and let's run the
script once again and then enter the
name so for entering the name for
example is right max told press enter
here just enter the second name for
example Tom and John I entered three
names here right and then print enter
and then it prints names and then
whatever names I have entered here right
now for example if you want to enter the
input on the same line as you printed
this echo string on then how you can do
this so for example I am going to run
this example once again and you can see
it prints the string using echo and then
I can see the prompt on the next line
now sometimes I want to do it on the
same line as this string right so how I
can do this so let me remove everything
here and let's say I want to allow the
user to enter his username right so I
can just write read and there is a flag
called
- P or P flag which allows us to enter
the you know input on the same prompt or
line right so for example I will just
write use a name here and then I can
take the user input for example user VAR
for user variable right so this will
allow me to enter the input on the same
line right and to echo this I can just
write echo and then whatever the user
name is so for example I will just write
the same text here and then the variable
name which is user var okay and let me
run the script once again and then it
asks me the user name for example my
user then press ENTER and it prints
their user name now sometimes you also
want to make this input silent silent
means for example you want to allow the
user to enter his password and the
password you can not show for example
right so you don't want to show what the
user is typing then you can use a flag
called ss4 flag right so let me just
show you what I mean so for with this
read you just add a s flag and then a
PFLAG and then for example this is a
password ok so just write password and
then just change the variable name for
example pass variable and then we will
just print our password ok so if you
want you you know skip this you can skip
this line because you don't want to show
whatever password you have entered but
this input will be silent
and let me show you what I mean by
silent is so let me run the script and I
will just enter the user name for
example my user
and then it asked me for the password I
enter the password one two three four
five but it doesn't show on this
terminal but it still it's stored in
this variable right so whenever you
press ENTER you can see the password
using this line of echo command
the password is shown here which is one
two three four five which I have printed
but in here I also can see that this
line is printed on the same line as the
password line so I fought to solve this
problem I can just write echo here with
no string right and let me run the
script once again so username my user
and password once again one two three
four five but it doesn't show on the
terminal and when I press ENTER it shows
everything so username and password like
this now for example you want to allow
the user to enter multiple inputs and
you want to save those input inside an
array so you can do that also
and for that you use a flag called
minus a so let me just you move
everything here and I will just say echo
and then I will just say enter names for
example inter names and then I can just
write read and then minus a which tells
this script to read an array right so
whatever variable name you give here for
example names it will be like an array
okay so to print those names I can just
write echo once again so just write echo
and then for example names and then
whatever names you have entered so I can
extract them like an array so to extend
extract an array you can just write the
variable name
in the index of the array so for example
at 0th index there will be a first name
but to print this variable you just need
to surround it by a curly bracket so
just give a curly bracket like this and
you can you know extract all the index
like this so next will be index 1 and
index 2 and index 3 and so on
right for example for now I just want to
expect what first two elements of an
array right so let me just run the
script once again a name once again
for example Tom and Max and then press
ENTER now it shows us the names so you
can extract those inputs as an array
also using this - a flag now I just want
to show you one last trick here so for
example I just wanted the user to enter
name normally and I will just remove
these inputs like this and for example I
just write read here with no variable
here after read command so what happens
when you write read command and no
variable after this so what happens is
whenever you write read and without any
variable after read c'mon the input goes
into a built-in variable called reply so
if you just write here dollar and then
reply then you will be able to see your
input even without your variable name so
the default variable in which your input
goes is this reply variable right so let
me clear the terminals here and now let
me run the script again so run the
script and for example I write some
named here once again max and then press
ENTER and it prints the name whatever I
have entered so by default your input
goes in this built-in variable called
reply so in this page you can read
variables in your script using terminal
I hope you enjoyed this video please
rate comment subscribe and bye for now
on shell scripting tutorial for
beginners in this video I'm going to
show you how you can read inputs from
your terminal in your script so to get
input from the keyboard you use read
command the read command takes input
from the keyboard and assigns it to a
variable so let's see how we can use it
so for example I want to allow the user
to enter some names so I will just write
for example first of all echo and then I
will just print some text for example
enter names or name right and then I
want to allow the user to enter the name
so for that I can use a command called
read and then whatever variable name I
right after this read command your input
will be saved in this variable okay so
for example I write the variable name
name then your input will be saved
inside this named variable now I want to
print this variable so I can just write
echo and then I can just write entered
name and then the variable so use dollar
symbol and the variable name as we have
seen in the last video so let's run the
script and let's see what happens so it
asks me for entering the name and I'll
enter some name for example Max and then
press ENTER and then it says entered
name is max which is totally fine right
so whenever you want to take an input
from the terminal use read command now
for example you want to enter multiple
variables in the same read command you
can just do that also so for example I
want a user to enter multiple name so I
will just edit this text to enter names
and then instead of using one variable
I can use for example name one and then
space name to let me just correct name
two and then space name three and so on
right so whenever you want the user to
input multiple variables just write the
variable and then separate it by the
space another variable separated by the
space and then another variable and to
print these names you can just print it
like you do normally for example names
and then first name is name one and then
comma for example and then once again
name - and then comma and then print
them variable name three okay
so let's save the code and let's run the
script once again and then enter the
name so for entering the name for
example is right max told press enter
here just enter the second name for
example Tom and John I entered three
names here right and then print enter
and then it prints names and then
whatever names I have entered here right
now for example if you want to enter the
input on the same line as you printed
this echo string on then how you can do
this so for example I am going to run
this example once again and you can see
it prints the string using echo and then
I can see the prompt on the next line
now sometimes I want to do it on the
same line as this string right so how I
can do this so let me remove everything
here and let's say I want to allow the
user to enter his username right so I
can just write read and there is a flag
called
- P or P flag which allows us to enter
the you know input on the same prompt or
line right so for example I will just
write use a name here and then I can
take the user input for example user VAR
for user variable right so this will
allow me to enter the input on the same
line right and to echo this I can just
write echo and then whatever the user
name is so for example I will just write
the same text here and then the variable
name which is user var okay and let me
run the script once again and then it
asks me the user name for example my
user then press ENTER and it prints
their user name now sometimes you also
want to make this input silent silent
means for example you want to allow the
user to enter his password and the
password you can not show for example
right so you don't want to show what the
user is typing then you can use a flag
called ss4 flag right so let me just
show you what I mean so for with this
read you just add a s flag and then a
PFLAG and then for example this is a
password ok so just write password and
then just change the variable name for
example pass variable and then we will
just print our password ok so if you
want you you know skip this you can skip
this line because you don't want to show
whatever password you have entered but
this input will be silent
and let me show you what I mean by
silent is so let me run the script and I
will just enter the user name for
example my user
and then it asked me for the password I
enter the password one two three four
five but it doesn't show on this
terminal but it still it's stored in
this variable right so whenever you
press ENTER you can see the password
using this line of echo command
the password is shown here which is one
two three four five which I have printed
but in here I also can see that this
line is printed on the same line as the
password line so I fought to solve this
problem I can just write echo here with
no string right and let me run the
script once again so username my user
and password once again one two three
four five but it doesn't show on the
terminal and when I press ENTER it shows
everything so username and password like
this now for example you want to allow
the user to enter multiple inputs and
you want to save those input inside an
array so you can do that also
and for that you use a flag called
minus a so let me just you move
everything here and I will just say echo
and then I will just say enter names for
example inter names and then I can just
write read and then minus a which tells
this script to read an array right so
whatever variable name you give here for
example names it will be like an array
okay so to print those names I can just
write echo once again so just write echo
and then for example names and then
whatever names you have entered so I can
extract them like an array so to extend
extract an array you can just write the
variable name
in the index of the array so for example
at 0th index there will be a first name
but to print this variable you just need
to surround it by a curly bracket so
just give a curly bracket like this and
you can you know extract all the index
like this so next will be index 1 and
index 2 and index 3 and so on
right for example for now I just want to
expect what first two elements of an
array right so let me just run the
script once again a name once again
for example Tom and Max and then press
ENTER now it shows us the names so you
can extract those inputs as an array
also using this - a flag now I just want
to show you one last trick here so for
example I just wanted the user to enter
name normally and I will just remove
these inputs like this and for example I
just write read here with no variable
here after read command so what happens
when you write read command and no
variable after this so what happens is
whenever you write read and without any
variable after read c'mon the input goes
into a built-in variable called reply so
if you just write here dollar and then
reply then you will be able to see your
input even without your variable name so
the default variable in which your input
goes is this reply variable right so let
me clear the terminals here and now let
me run the script again so run the
script and for example I write some
named here once again max and then press
ENTER and it prints the name whatever I
have entered so by default your input
goes in this built-in variable called
reply so in this page you can read
variables in your script using terminal
I hope you enjoyed this video please
rate comment subscribe and bye for now
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Dec 22, 2024 Last updated |
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