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Linux : Basic Commands

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Shivam Anand
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Linux :

Linux, an open-source operating system, is a powerful and versatile platform that has become the backbone of modern computing. Its flexibility, security, and a wide array of commands make it an essential tool for developers, sysadmins, and enthusiasts alike. Linux provides a command-line interface that enables users to interact with the system efficiently and perform various tasks, from simple file management to complex network configurations.

Basic Commands:

  • pwd: It gives the present working directory.
$ pwd
/home/user/projects/my_project
  • echo: echo command is used to display text or messages in the terminal or command-line interface
$ echo "Hello, World!"
Hello, World!

//Using Escape Sequences
$ echo "First Line\nSecond Line\nThird Line"
First Line
Second Line
Third Line
  • ls: command in Linux is used to list files and directories in the current working directory. It provides valuable information about the contents of a directory, such as file names, permissions, ownership, size, and modification timestamps.
// Listing files and directories

$ ls
file1.txt  file2.txt  directory1  directory2

//Displays information like file permissions,hard links,owner, group, 
file size, timestamp, and the name of each file/directory.

$ ls -l
-rw-r--r-- 1 user user 1024 Aug 1 10:00 file1.txt
-rw-r--r-- 1 user user 2048 Aug 1 11:00 file2.txt
drwxr-xr-x 2 user user 4096 Aug 1 12:00 directory1

//Hidden Files

$ls -a

//Files size human readable like "K" for kilobytes

$ ls -lh
-rw-r--r-- 1 user user 1.0K Aug 1 10:00 file1.txt
-rw-r--r-- 1 user user 2.0K Aug 1 11:00 file2.txt

  • whoami: Command in Linux is used to display the current user's username.

  • cd: Change Directory, It allows you to navigate to different directories within the file system.

// To a particular directory
$ cd Documents

//Home Directory
$ cd ~

//Parent Directory (One Level Up)
$ cd ..
  • mkdir: Command in Linux is used to create directories or folders. It allows you to create single directories, multiple directories, and nested directories.
//Single directory
$ mkdir new_folder

//Multiple directory
$ mkdir folder1 folder2 folder3

//Nested directory
$ mkdir -p A/B/C/D/E
  • touch & cat: Commands in Linux are used for creating and viewing files, respectively. The touch command is used to create empty files or update the timestamp of existing files.
//Empty file
$ touch file.txt

//View Contents of a file
$cat file.txt

//Creating a new file with content 
$cat > newfile.txt
This is my first file
(Press CTRL+D to save and exit)

//Combine multiple files into one
$ cat file1.txt file2.txt > combined_file.txt

//Appending content to existing file
$ cat new_content.txt >> existing_file.txt

//Display content with line numbers
$ cat -n file.txt
   1  Line 1
   2  Line 2
   3  Line 3

  • Basic editors:

    • Vi/Vim: A classic and powerful modal text editor.

    • Nano: It is a user-friendly and straightforward editor for beginners.

    • Sublime Text: Fast, simple, and extensible editor with a free evaluation version.

Creating a fruits.txt and fruits1.txt with Vi editor:

  1.  $vi fruits.txt
 (Editor will open , Press 'i' for insert mode
  and enter the data. To save and exit  press 'ESC+ :wq')

 $vi fruit1.txt
 (Repeat the same process as above)

  2. head, tail, and diff commands: Commands in Linux are used to display the top and bottom lines of a file, respectively.

    1. diff command in Linux, the notation "1c1" represents a change that has occurred between two files being compared.

    2. General Format of the diff

       line_number_1cchange_type line_number_2

      • line_number_1The line number in the first file where the change occurred

      • change_typeThe type of change that occurred. The most common change types are:

        • cindicates that a change (modification) has occurred in the line.

        • aindicates that a new line has been added in the second file.

        • dindicates that a line has been deleted from the first file.

      • line_number_2The line number in the second file where the corresponding change occurred

In conclusion, Linux commands offer a powerful and efficient way to interact with the operating system through the command-line interface.

Thank you for taking out valuable time and effort to read till the very end; feedback is always welcomed and appreciated.

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