Linux: This Book Includes 4 Manuscripts. The Underground Bible to the unix operating System with Tools On Security and Kali Hacking to Understand Computer Programming, Data Science and Command Line

The command works as follows:
type echo
The output is as follows:
echo is a built-in shell 
Another example,
type trump
The output is as follows:
Trump is not a built-in shell
Also, remember that two dots that is (••) is used to determine the successful
working or execution of the script. Here are the in-built commands we are
going to discuss in detail.
1) Alias
Normally Linux commands are a little trickier to type. I suppose you have
to type echo every time it may be difficult. For this reason, you can use an
alias to give shortcut for a command.
Below we describe the command that needs to be entered to make alias
work.
example@ linuxwar : Alias groupecho
However, it should be remembered that aliases work only until the shell
environment is open. That is if the shell is exited there is no way to access it
again. Also, the alias functions are stored in the bashrc directory of the user
environment. Aliases are an easy way to increase productivity. Hackers use
a lot of aliases to make deciphering the script a lot trickier. 
2) Unalias

As you might have guessed already unalias is used to delete the alias
systems that are present. By using this command, you can delete any alias
command that you have created before.
Below is the command that will let us understand how it works:
example@ linuxwar : unalias groupecho
You can also use -a to delete all the aliases that are present at once.
However, as we said before ending a shell environment will delete all the
aliases that are present but using unalias. will help you to delete things
while you are still scripting.
3) bg,fg,jobs
A lot of shellcode is done in interactive mode. Sometimes when you are
trying to exploit a system you need to perform various tasks at once. These
tasks are called jobs in Linux terms. So for everyone's convenience jobs are
divided into two types. The first one is a foreground job where we can see
the procedure that is going on. The classic example of foreground jobs is
the installation of system programs. You can't handle other jobs while doing
foreground jobs. 
Solely, for this reason, background jobs are developed. Background jobs
can help things run in the background. Hackers should be well aware of this
because they are ought to work with multiple processes. 
Below are the commands for the job functionalities:
example@ linuxwar : bg job 1
example@ linuxwar : fg job2
example@ linuxwar : view jobs
4) cd
Cd is the classic Linux shell command that is famous for its huge usage.
When performing tasks users usually are thrown into the root directory by

the shell. Huge usage of root directory can make it scattered and messy. For
this reason, Linux users use CD to change their directory and perform
actions. 
Below is the command for the change directory:
example@ linuxwar : cd /etc/read

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