LINUX
Advantages of Linux
It was the year 1991, a young lad named Linus Torvalds, a 21-year-old computer science student, was frustrated with the limitations of the current paid operating systems. The only open source at that time was UNIX, which was not well-suited for his needs. So he created a new, spiraling system called Linux, which was an open source system that was free to modify and use.
Well, if you’ve noticed, I’ve already listed advantages of Linux like open source and customizable, but there are many more to go. Like, Linux has an additional language that works only on Linux — shell scripting — which generally doesn’t require a compiler.
Besides that, Linux focuses on efficiency. When you give it a task, it will only invest its energy and resources to complete that given task. There’s nothing working in the background. Imagine if we humans had that clarity that’s the efficiency!
The biggest feature Linux has to offer is security. It is the most precious thing one could ask for, and Linux providing that for free is crazy!
Linux ticks every box of what a good operating system should.
2) Commands and Scenario:
1)echo
Concept : displays anything
Syntax : echo “Text”
Scenario : I want to display Hello World
2)date
Concept : displays current date
Syntax : date
Scenario : I want to display today's date
3)cal
Concept : Displays current calendar
Syntax : cal
Scenario : I want to know the present month and day
4)read
Concept : To save variable
Syntax : read variable_name
Scenario : Shoeb wants to take a variable from the user and save it.
5)mkdir
Concept : to create a new directory
Syntax : mkdir folder_name
Scenario : I want to create a new directory for my project.
6)cd
Concept : To change the directory
Syntax : cd directory_name
Scenario : I want to work in my project directory
7)ls
Concept : List of files in the current working directory
Syntax : ls
Scenario : I got into my old directory but I don’t remember the files so I use ls
8)touch
Concept : 1)If file doesn’t exists it creates a new file
2)If file already exists it updates the file
Syntax : touch file_name_with_extension
Scenario : I created new file linux.txt with touch then I added a few more lines so to update I used touch again.
9)cp
Concept : Used to copy 1 file to another
Syntax : cp Source Destination
Scenario : I wanted to copy linux.txt to fedora.txt
10)pwd
Concept : displays current working directory
Syntax : pwd
Scenario : I wanted to see the directory I was working in
11)cat
Concept : it displays the file content
Syntax : cat file_name_with_ext
Scenario : I wanted to check the file content of linux.txt
12)man
Concept : Access manual for all files
Syntax : man command
13)grep
Concept : search for specified in a mentioned or specified thing
Syntax : grep string_you_want_to_search file_name_ext
Scenario : I want to search mit in linux.txt
14)whoami
Concept : displays current user
Syntax : whoami
Scenario : I want to know who accessed my pc
15)sed
Concept : used to edit or remove text
Syntax : sed [options] script [file]
1) i:in place editing
2)n:supress automatic print
Scenario : I want to remove a particular line in linux.txt
16)head
Concept : displays contents top line in the file
Syntax : head -n no of lines file name
Scenario : I wanted to display the top 4 lines in linux.txt
17)tail
Concept : it displays the contents of bottom lines in the file
Syntax : tail -n no of lines file name
Scenario : Teacher wanted to know who were the bottom 5 in the class so she used tail in class.txt.
18)Decision making statement
Concept : Wherever there are 2 possibilities
Syntax : If [condition]
then
else
fi
Scenario : echo “1 for yes, 2 for no”
read a
if [(($a) le 1)]
then
echo “Yes”
else
echo “No”
fi
19)Loop
Concept : Used to make iterations that are multiple back and forth trips
Syntax : while [ ]
do
done
Scenario : i = 10
while [ i -ge 5 ]
do
echo "$i"
i = i - 1
done
20) Line Concatenation
Concept : to display a line in front of a line
Syntax S = "$( first line input ) $(second line input)
Scenario :
echo : " Enter your college"
read n
echo : "Enter your college City"
read s
S = "$n $s"
echo "Your college is $S"
21 ) String comparison
Concept : compares two strings with scrutinizing every letter
Syntax + Scenario :
S1 = PASSWORD
S2 = password
If [[ "$S1" =~ "$S2" ]]
then
echo " access "
else
echo "access denied"
fi
22) Switch case
Concept : Allows condition branching with the help of cases
Syntax : variable = a
Case "$a" in
("Case 1") echo " text " ;;
("Case 2") echo " text" ;;
esac
Scenario :
a=people
case "$a" in
"Xyz") echo "Enemies" ;;
"Pqr") echo "Friends" ;;
esac
23) For loop
24) function
25)Continue
26) Break
3 Conclusion and Commands
In a language for instance maybe English ,Hindi , Marathi etc Grammar plays an important role in molding the sentence in a way that our brain could process and understand it.Similarly these commands do the same work here so understanding them is a quint essential for one who wants to master linux , below are the commands with quick summary
1)echo : It is used to display anything on the screen
2)date : It is used to display the current date
3)cal : It is used to display the current calendar
4)read : It is used to take input from the user and save it in a variable
5)mkdir : It is used to create a new directory
6)cd : It is used to change the directory
7)ls : It shows the list of files in the current working directory
8)touch : It creates a new file or updates an existing file
9)cp : It is used to copy one file to another
10) pwd : It displays the current working directory
11) cat : It displays the content of a file
12)man : It is used to access the manual of any command
13)grep : It is used to search for a given word inside a file
14)whoami : It displays the current user
15)sed : It is used to edit or remove text in a file
16)head :It displays the top lines of a file
17) tail : It displays the bottom lines of a file
18)Decision making : It is used when there are two possible outcomes
19)Loop : It is used to perform repeated actions multiple times
20) Line concatenation : It is used to join two lines or strings together
21)String comparison : It is used to compare two strings letter by letter
22)Switch case : It allows branching based on different cases
23)continue : skips the current loop step and moves to the next.
24) break : stops the loop completely
25 ) for loop: repeats a set of commands for each value in a list
26) function: a reusable block of code you can call anytime
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