Handling File Uploads and Working with File Systems in PHP

February 24, 2024

In this post, we will explore file handling in PHP, including uploading files, reading and writing to files, and interacting with the file system. File handling is an essential aspect of web development, as it allows us to work with user-uploaded files, store data, and manage the file system on the server.

Uploading Files in PHP

One common requirement in web applications is to allow users to upload files, such as images, documents, or media files. PHP provides the $_FILES superglobal array to handle file uploads. When a file is uploaded via a form, PHP stores the file information in the $_FILES array, including the file’s name, type, size, and temporary location on the server.

<?php
if(isset($_FILES['file'])) {
  $file = $_FILES['file'];
  $file_name = $file['name'];
  $file_tmp_location = $file['tmp_name'];
  $file_size = $file['size'];
  $file_type = $file['type'];
  // Process the uploaded file
}
?>

After receiving the file upload, you can move the file to a permanent location on the server using the move_uploaded_file function. It’s important to validate and sanitize user-uploaded files to prevent security vulnerabilities.

Reading and Writing to Files

PHP provides various functions for reading and writing to files. You can use the file_get_contents function to read the contents of a file into a string, or file function to read the file into an array of lines. Similarly, you can use the file_put_contents function to write data to a file.

<?php
// Reading from a file
$file_content = file_get_contents('example.txt');

// Writing to a file
file_put_contents('output.txt', 'Hello, World!');
?>

When working with files, it’s important to handle errors and exceptions that may occur during file operations. Always check for file existence and permissions before reading from or writing to a file.

Interacting with the File System

PHP provides a range of functions for interacting with the file system, such as creating, deleting, and modifying directories and files. You can use the mkdir function to create a new directory, rmdir to remove a directory, and unlink to delete a file.

<?php
// Creating a directory
mkdir('new_directory');

// Deleting a file
unlink('old_file.txt');
?>

When working with the file system, always ensure that you have the necessary permissions to perform the desired operations, and handle errors gracefully to provide a smooth user experience.

File handling in PHP is a fundamental aspect of web development, and mastering these techniques will enable you to build robust and dynamic web applications. Whether you’re working with user-uploaded files, managing data storage, or interacting with the file system, PHP offers powerful capabilities for file handling.