Command Prompt

what is sh, the most time command-line??

• In a Markdown file, sh refers to the "Bourne Shell", a command-line interpreter and programming language for Unix-like operating systems.
• note:- The sh command typically refers to the Unix shell and is not directly applicable to the Windows Command Prompt or PowerShell environments.

Command Prompt vs Powershell

• Command Prompt (cmd.exe) -> Command Prompt is the traditional command-line interpreter in Windows, tracing its roots back to MS-DOS.2
  • Functionality: It's suitable for basic tasks like navigating the file system, running simple utilities, and executing batch scripts.5
• PowerShell -> PowerShell is a more modern and powerful command-line shell and scripting language built on the .NET framework.6
  • Functionality: It's designed for system administration, automation, and advanced tasks.9

What is Unix- like shell? common Unix-like shells that are available on Windows 1. Bash (Bourne Again Shell) such as Git Bash:**

Directory Separator

• Windows:
  • Uses the backslash (\) as the directory separator.
  • C:\Users\YourName\Documents\myfile.txt
• Unix-like systems (Linux, macOS, etc.):
  • Use the forward slash (/) as the directory separator.
  • /home/yourname/documents/myfile.txt

Commands

touch (Unix-like Shells) : It update the access and modification timestamps of a file. (Creates if doesn't exist)

nul (Window Cmd) : It is a special device in Windows, essentially a "black hole" for output. Anything redirected to nul is discarded.

type (Windows Cmd) : It is used to display the contents of a file.

echo (Unix-like Shells and Windows Cmd) : It is used to display provided arguments (text or variables).

> (Redirection Operator)

• It is a redirection operator. It redirects the output of a command to a file.

Clean Terminal

clear

Remove a file (In Window)

# Remove a file
del path\to\your\file
 
# Remove a Folder
rmdir /s /q path\to\your\folder

/s: option removes the folder and its contents /q: suppresses confirmation prompts

Understand type & nul

# Output nothing into a file (Used to Create a empty file or overwrite if exist)
nul > app.js
#or
> app.js
 
# display content from a file
type app.js
 
# display and store nothing into a file
type nul > app.js
 
# display and output content into a file 
type Hello world > app.js # Not Valid ❌

Display an output type/echo

type app.js
 
echo app.js ❌ # output string i.e. app.js

• type <file> : display the contents of a file in the terminal (Windows Command Prompt).
• echo <file> : prints the string provided after it to the terminal. in this case print filename, not its content

Create a empty file or clear a file. >

# Creates a empty file or overwrites
nul > index.html
# or shorthand
> index.html
 
# unix-based system.
touch index.html

Create or overwrite empty file and display file > & type/echo

type nul > app.js
# or
echo > app.js

• type nul : It is used to output nothing (nul system null)
• echo : this by itself outputs a blank line

Create or overwrite text in a file

# create or clear a file
echo > app.js
 
# create or overwrite a file with a 'single blank line'
echo. > app.js
 
# create or overwrite a file with 'Hello World' text
echo Hello world > html.txt

Cntrl+ C

is used to terminate a running Process in Unix-like Operating System + cmd & shell

Comment

REM

REM This is a comment

::

:: This is a comment

echo ?

The echo command in Unix-like operating systems, including Linux and macOS, as well as in the Windows Command Prompt and PowerShell, is used to display a line of text or a string.

Syntax

echo [option(s)] [string(s)]

Display a simple message

echo "Hello, World!"

note:- like powershell "" is not used in cmd

Write output to a file (create file if not exist)

echo Hello, world! > myfile.txt

Display the value of a variable

name="Gaurav"
echo "Hello, $name!"

Print multiple lines

echo -e "Line 1\nLine 2\nLine 3"

Common Options

• -e: Enable interpretation of backslash escapes (like \n for newline).
• -n: Do not output the trailing newline.
• -E: Disable interpretation of backslash escapes (default behavior).

Using incorrect directory separators

(e.g. require('.\myFile.js'), when it should be .//myFile.js. Remember,

• Windows systems use backslashes while Unix-like systems use forward slashes