♾️ DevOps and 🐧 Linux Commands: A Powerful Duo🔥

👉 Quick Intro

• Linux is open source, which means it is free and you can make any changes in the source code and use your own Linux

• Linux has multi-user support

• Linux Torvalds used Unix OS to create his own OS, which is named Linux

• It's essential to understand the fundamental Linux commands and how to use them effectively. This comprehensive guide will take you through a detailed exploration of these commands.

👉 Command Line Interface 🧑‍💻

CLI is like talking to a computer using special words (commands), you type in commands, and the computer does what you say. It's a bit like magic 🪄 words to make your computer do things.

What does CLI look like?

let's see what is written in CLI

• user name of logged-in user

• computer name

• ~ is the home directory of logged-in user, which in this case is /home/ec2-user

• # at the end represents the root user, like the admin user in Windows

• $ at the end represents a normal user

• pwd is a present working directory

👉 Types of files

• Ordinary File / Normal File 📝

  • start with '-' in the ls -l command

  • contains data like text, images, audio, video, etc.

• Directory File [folder] 📂

  • start with 'd' in the ls -l command

  • contains all kinds of files in it

• Link File 🔗

  • start with 'l' in the ls -l command

  • it is a link to another file

look at the first character of each line

👉 Let's start with Commands ⚙️

1. Basics commands ✔️

   pwd - present working directory, the current location of a user in the file structure

   cd - change directory

   whoami - it will display the current logged-in username

   who - shows logged-in users of the system

   date - display current date with time

   cal - display calendar

   history - get all commands that are executed in the past

   history n - get only 'n' recent commands that are executed in the past

   man <command> - it will give documentation of the command

   unzip <zip-file> - extract the zip file

   tar -xvzf <tar-file> - extract the tar file

2. 

   Create or delete files and directories 📝

   touch <file> - create an empty file

   touch <file1> <file2> ... - create multiple empty files

   touch file{1..5}.txt ... - create multiple empty files with numeric names as file1.txt file2.txt ... file5.txt

   

   cat > <file> - create a file with data [ctrl+d to save and exit]

   cat >> <file> - append file with data [ctrl+d to save and exit]

   cat <file> - display data in the file

   

   mkdir <dir> - create directory

   mkdir <dir1> <dir2> - create multiple directories

   mkdir -p dir1/dir2/dir3/dir4 - create nested directories

   mkdir dir{1..5}.txt ... - create multiple empty directories with numeric names as dir1.txt dir2.txt ... dir5.txt

   

   rm <file> - delete file

   rmdir <dir> - delete an empty directory

   rmdir <dir1> <dir2> - delete multiple empty directories

   rm -d <dir> - delete an empty directory

   rm -r <dir> - delete a non-empty directory

3. 

   File operations ⚙️

   cat file1 > file2 - copy content of file1 to file2

   cat file1 file2 > file3 - copy content of file1 & file2 to file3

   cp file1 file2 - copy content of file1 to file2

   cp -r dir1 dir2 - copy all files from dir1 to dir 2

   mv file1 file2 - rename or move file or dir

   cmp file1 file2 - display only the first difference

   diff file1 file2 - display all differences

4. 

   List files 📃

   ls - used to list files and dir in current dir [alphabetical order]

   ls <dir> - used to list files and dir in a given dir

   🚩 FLAGS

   ls -l - list files and dir with info

   

   ls -r - ordering files reversely alphabetical order

   ls -t - list files and dir by ordering them based on modified date and time

   ls -tr - ordering files reversely based on modified date and time

   ls -ltr

   ls -a - list hidden files also

   ls -R - shows files and dir with subdirectories content

5. 

   Read file data and details ✔️

   wc <file> - display no. of lines, words, and characters in the file

   

   🚩FLAGS

   -l --> Display only the number of lines

   -w --> Display only the number of words

   -c --> Display only the number of characters

   

   cat <file> - display the content of the file

   cat -n <file> : display the content of a file with line number

   tac <file> : display the content of the file line-wise from bottom to top

   rev <file> : each line in reverse order from top to bottom

   

   head <file> : display top lines of file [default is 10]

   head -n <number> <file> : display top n lines

   tail <file> : display bottom lines of file [default is 10]

   tail -n <number> <file> : display bottom n lines

   tail -n +<number> <file> : display lines from nth to last

   

   grep 'text' file : display matched lines with the file name

   grep 'text' * : search text in all files in the current dir

   grep -n 'text' : display matched lines with line number

   grep -l 'text' : display only file name

   grep -L 'text' : display file names that do not contain

   grep -v 'text' : Invert the string match

   grep -i 'text' file : search text in file [case insensitive]

   grep -R 'text' : search text in all subdirectory file

   grep ^text file : display lines that start with a text

   grep text$ file : display lines that end with a text

   

These basic Linux commands provide you with a solid foundation for navigating and managing your Linux system. As you continue your journey with Linux, you'll discover additional commands and tools that will empower you to perform more advanced tasks and streamline your system administration and development activities. Linux's robust command-line interface offers endless possibilities for customization, automation, and control, making it a powerful and versatile platform for a wide range of use cases.

Happy Learning !!! 👋