PHP readfile( ) Function - GeeksforGeeks

PHP readfile( ) Function

Last Updated : 29 Oct, 2026

The readfile() function in PHP reads a file and writes its contents directly to the output buffer. It is commonly used to display file contents in a browser or serve files for download.

Syntax:

readfile(string $filename, bool $use_include_path = false, ?resource $context = null): int | false

Parameters:

  • $filename: Specifies the path of the file to read.
  • $use_include_path: Optional Boolean parameter. Set it to true to search for the file in PHP's include_path.
  • $context: Optional stream context that specifies additional options for accessing the file or URL.

Return Value:

  • Returns the number of bytes read and written to the output.
  • Returns false if the operation fails.

Reads a File Using readfile()

The following example reads and displays the contents of a text file named notes.txt.

notes.txt

Welcome to PHP!
This is a demo file.
Have a great day!
PHP 
<?php
echo "Contents of notes.txt:\n";

$bytesRead = readfile("notes.txt");

echo "\nTotal bytes read: " . $bytesRead;
?>
  • readfile() reads the entire file and writes its contents directly to the output.
  • The function returns the number of bytes read and written.
  • The returned value can be stored in a variable for further processing.

Output:

Screenshot-2026-10-29-113927

Note: The byte count depends on the exact contents of the file, including line endings.

Whether a File Is Readable Before Using readfile()

Use is_file() and is_readable() to check whether the specified path refers to a readable file before attempting to read it.

PHP 
<?php
$file = "document.txt";

if (is_file($file) && is_readable($file)) {
    readfile($file);
} else {
    echo "Unable to access the file.";
}
?>
  • is_file() checks whether the path refers to a regular file.
  • is_readable() checks whether the file is readable by the PHP process.
  • readfile() outputs the file contents if the checks pass.

Note: These checks do not guarantee that the subsequent read will succeed, so handle possible read failures as well.

Output:

Screenshot-2026-10-29-115117

Displays an Image Using readfile()

The readfile() function can serve an image directly to the browser. Set the appropriate Content-Type header before outputting the image data.

PHP 
<?php
$imagePath = "gfg.png";

if (is_file($imagePath) && is_readable($imagePath)) {
    header("Content-Type: image/png");
    readfile($imagePath);
    exit;
}

http_response_code(404);
echo "Image not found.";
?>
  • $imagePath specifies the image file.
  • header("Content-Type: image/png") tells the browser to interpret the response as a PNG image.
  • readfile() sends the image data to the output.
  • exit prevents additional output from being appended to the image response.

Output:

file

Downloads a File Using readfile()

To prompt the browser to download a file, use the Content-Disposition: attachment header along with the appropriate content type.

PHP 
<?php
$fileToDownload = "report1.csv";

if (is_file($fileToDownload) && is_readable($fileToDownload)) {
    header("Content-Type: text/csv");
    header(
        'Content-Disposition: attachment; filename="' .
        basename($fileToDownload) . '"'
    );

    readfile($fileToDownload);
    exit;
}

http_response_code(404);
echo "Download failed: File not found.";
?>
  • Content-Type: text/csv identifies the response as CSV data.
  • Content-Disposition: attachment prompts the browser to download the file.
  • basename() extracts the filename for the download header.
  • readfile() sends the file contents to the browser.

Note: In a real application, validate and authorize access to the requested file. Do not allow untrusted user input to determine arbitrary filesystem paths.

Best Practices

  • Check file paths and permissions before reading files.
  • Send the appropriate HTTP headers before outputting file contents.
  • Avoid printing HTML, whitespace, or debugging messages before sending headers.
  • Do not use the @ operator to suppress errors as a substitute for proper error handling.
  • Restrict access to sensitive files and validate file paths to prevent unauthorized access.
  • Use the appropriate content type when serving images, documents, or downloadable files.
Comment

Explore