🗂️ ASP – File System API: Drive, TextStream Objects Explained

Classic ASP provides the FileSystemObject (FSO) to interact with the server’s file system. Using this powerful API, developers can read, write, create, delete, and inspect drives, folders, and text files. Two of the most commonly used objects in this API are:

• Drive: Used to get drive-level information (C:, D:, etc.)
• TextStream: Used for reading and writing text files

This article walks you through how to use both effectively in Classic ASP.

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🧠 Introduction to FileSystemObject

The FileSystemObject (FSO) is a COM component used in Classic ASP via VBScript to perform file I/O operations on the server.

✅ How to Create FSO:

<%
Set fso = Server.CreateObject("Scripting.FileSystemObject")
%>

Key Components of FSO:

• Drives, Drive
• Folder, File
• TextStream

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💽 Working with Drive Object

The Drive object provides information about physical drives on the server.

🔍 Example: Accessing Drive Info

<%
Set fso = Server.CreateObject("Scripting.FileSystemObject")
Set drive = fso.GetDrive("C:")

Response.Write "Drive Letter: " & drive.DriveLetter & "<br>"
Response.Write "Drive Type: " & drive.DriveType & "<br>"
Response.Write "Free Space: " & drive.FreeSpace & "<br>"
Response.Write "Total Size: " & drive.TotalSize & "<br>"
Response.Write "Volume Name: " & drive.VolumeName & "<br>"
%>

🧾 Output Might Be:

Drive Letter: C
Drive Type: 2  ' (2 = Fixed Drive)
Free Space: 4294967296
Total Size: 10737418240
Volume Name: OS_Drive

🧠 Note: DriveType returns an integer (0 = Unknown, 1 = Removable, 2 = Fixed, 3 = Network, etc.)

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📄 Reading Files with TextStream

To read a file, you use the TextStream object returned by the OpenTextFile method.

📘 Example: Reading Line by Line

<%
Set fso = Server.CreateObject("Scripting.FileSystemObject")
Set file = fso.OpenTextFile("C:\data\info.txt", 1)  ' 1 = ForReading

Do While Not file.AtEndOfStream
    Response.Write file.ReadLine & "<br>"
Loop

file.Close
%>

📌 Modes:

• 1 – ForReading
• 2 – ForWriting
• 8 – ForAppending

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✏️ Writing to Files with TextStream

You can create or write to files using FSO and TextStream.

✍️ Example: Writing to a File

<%
Set fso = Server.CreateObject("Scripting.FileSystemObject")
Set file = fso.CreateTextFile("C:\data\output.txt", True)

file.WriteLine("Hello, world!")
file.WriteLine("Welcome to ASP File System.")

file.Close
%>

📌 The second parameter of CreateTextFile(path, overwrite) allows overwriting if set to True.

🧾 Example: Appending to File

Set file = fso.OpenTextFile("C:\data\output.txt", 8, True)
file.WriteLine("New line added.")
file.Close

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🧪 Full ASP Example Using Drive & TextStream

<%
Set fso = Server.CreateObject("Scripting.FileSystemObject")

' Get drive info
Set drive = fso.GetDrive("C:")
Response.Write "<h3>Drive Info:</h3>"
Response.Write "Free Space: " & drive.FreeSpace & "<br>"

' Write to a new file
Set writer = fso.CreateTextFile("C:\data\report.txt", True)
writer.WriteLine("Report Generated")
writer.WriteLine("Drive Free Space: " & drive.FreeSpace)
writer.Close

' Read and display the file content
Set reader = fso.OpenTextFile("C:\data\report.txt", 1)
Response.Write "<h3>Report Contents:</h3>"
Do While Not reader.AtEndOfStream
    Response.Write reader.ReadLine & "<br>"
Loop
reader.Close
%>

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🛑 Common Errors and Best Practices

⚠️ Issue	💡 Solution
Permission Denied	Ensure IIS has write access to the directory
Path Not Found	Use absolute path (C:\...), not virtual path
File Not Found	Check file existence with fso.FileExists(path)
Script Timeout	Avoid large files; increase timeout if needed
Security Risk	Never expose full paths to user input

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✅ Summary

• FileSystemObject lets you manipulate files and folders using VBScript in Classic ASP.
• Use the Drive object to get storage information.
• Use the TextStream object to read and write text files.
• Always handle exceptions and file access carefully on a live server.

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❓ FAQs

Q1. Can I use FileSystemObject in ASP.NET?
Yes, but ASP.NET offers better classes like System.IO.File and Directory.

Q2. How can I check if a file exists before reading?
Use:

If fso.FileExists("C:\data\file.txt") Then
    ' Proceed to open
End If

Q3. How do I append instead of overwrite a file?
Open the file with mode 8 (ForAppending).

Q4. Is FileSystemObject secure?
It’s powerful but dangerous if mishandled. Never let users supply paths directly.

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