what exactly is a Shell in ubuntu or Linux

 """
shell ==>
1.The default interface to linux
2. The program that accepts your commands and execute those commands
3. Also called commandline interpreter

To acess it on ubuntu desktop/laptop(ctrl+alt+t)
when shell(Terminal emulator application) is opened it shows you prompt.Prompt waits for you to type something in it.
(type whoami)


question: Why use a CLI when we have graphical interdace?
If you want to acess some linux server ,most server distributions doesn't include GUI.
There will be many tedious tasks like renaming a 1000 files....
So in GUI you have to right click and rename,but if you get familiar with commandline you can do it with a command..


Normal VS root

A prompt  will typically look like
[username@computername ~]$
But if you want to have more privelages then you need to change to root prompt.
[root@computername:~]#
To change to root prompt you have to type
An Example from my laptop

cam@hack3r:~$ sudo su
[sudo] password for cam:
root@hack3r:/home/cam#

Observe there is a different symbol for root at the end(#)

Question:
Now in the last post we've discussed a root (directory),mother of all directories.Is that root is same is this root prompt??
No..That is a directory.This root is an account,like super account.

Root,The Superman account
It's like Administrator account in windows.
I've an account called cam on my laptop..
cam<root
for that matter any account on my ubuntu have less privelages than root.


Question:
Why is there a root account when i can access it with a simple command.why can't my user account have all privelages?
Answer:
Simple,In most linux servers there will be multiple user with different tasks...
Only system admins have access to root.You might have seen in many movies people trying to access root.


Tilde(~) Expansion

wait i've seen this somewhere??
Yes it's on your prompt and it is called Tilde

~cam = /home/cam
~root=/root
~ftp = /srv/ftp

Try out these:

cam@hack3r:~$ sudo su
[sudo] password for cam:
root@hack3r:/home/cam# pwd
/home/cam
root@hack3r:/home/cam# cd ~
root@hack3r:~# pwd
/root
root@hack3r:~# cd ~cam
root@hack3r:/home/cam# pwd
/home/cam
root@hack3r:/home/cam# exit
exit
cam@hack3r:~$



Take out from this post



===========                        ==========
command                          Action
===========                        ==========

1.pwd                             displays present working directory

2.cd                             Change directory[you cannot type any directory.You've type the exact path]

3.sudo su                         To access root account from terminal

4.exit                             To exit from root account to normal account(Use root account carefully..)

5.Clear                            Clears the terminal application















 

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