How can file permissions (chmod) affect the ability to access and write to files in PHP?

File permissions (chmod) can affect the ability to access and write to files in PHP by restricting or allowing certain actions based on the permissions set for the file. If the file has restrictive permissions, PHP may not be able to read from or write to the file, resulting in errors or unexpected behavior. To solve this issue, you can use the chmod function in PHP to set appropriate permissions before accessing or writing to the file.

// Set appropriate permissions for the file
chmod("path/to/file.txt", 0644);

// Read from the file
$fileContent = file_get_contents("path/to/file.txt");

// Write to the file
file_put_contents("path/to/file.txt", "Hello, World!");