07-Shift-User-Input.md

🔁 SHIFT Command and SET /P for User Input

• Batch scripting can do more than static automation — with tools like SHIFT and SET /P, you can process dynamic input and build interactive scripts.

  🔄 The SHIFT Command

  • The SHIFT command shifts all command-line arguments one position to the left.

    It enables batch scripts to handle more than %9 arguments — critical for loops and bulk operations.

    ✅ Syntax

    SHIFT [/n]

    • /n — Optional, specifies the starting argument to shift from (rarely used in practice)

    ---

    🧪 Basic Example: Print All Arguments

    @ECHO OFF
    :loop
    IF "%1"=="" GOTO end
    ECHO Arg: %1
    SHIFT
    GOTO loop
    :end

    📌 Run it like this:

    showargs.bat one two three four five six seven eight nine ten eleven

    ✅ Output:

    Arg: one
    Arg: two
    ...
    Arg: eleven
    

    🧠 Use Case: Processing a List of Files

    @ECHO OFF
    :process
    IF "%1"=="" GOTO done
    ECHO Processing file: %1
    :: Place your logic here
    SHIFT
    GOTO process
    :done
    ECHO All files processed.

---

🧾 SET /P – Accepting User Input

• SET /P allows your batch script to prompt the user for input — like a simple interactive prompt.

  ✅ Syntax

  SET /P variable=Prompt text

  ---

  🔹 Simple Example

  @ECHO OFF
  SET /P name=Enter your name: 
  ECHO Hello, %name%!

  🖥️ Output:

  Enter your name: Alice
  Hello, Alice!
  

  ---

  🛡️ With Validation

  @ECHO OFF
  :ask
  SET /P age=Enter your age: 
  IF "%age%"=="" (
      ECHO Age is required!
      GOTO ask
  )
  ECHO Your age is: %age%

  ---

  🧪 Password Entry Simulation (not secure)

  SET /P pass=Enter password: 
  IF "%pass%"=="secret" (
      ECHO Access granted.
  ) ELSE (
      ECHO Access denied.
  )

  ---

  🧠 Combining SHIFT and SET /P

  You can combine both to create dynamic + interactive scripts:

  @ECHO OFF
  SET /P confirm=Start processing arguments? (Y/N): 
  IF /I NOT "%confirm%"=="Y" EXIT /B
  
  :loop
  IF "%1"=="" GOTO end
  ECHO Processing %1
  SHIFT
  GOTO loop
  :end