PHP can read and write files using file_get_contents(), file_put_contents(), and fopen(). This is useful for logs, config files, and processing uploads. Always validate file paths from user input to prevent security issues.
File Handling
// Read entire file
$content = file_get_contents("data.txt");
// Write to file
file_put_contents("data.txt", "Hello!");
file_put_contents("data.txt", "more\n", FILE_APPEND);
// Read line by line
$lines = file("data.txt"); // array of lines
$handle = fopen("data.txt", "r");
while (!feof($handle)) {
$line = fgets($handle);
}
fclose($handle);
// File info
file_exists("data.txt"); // true/false
filesize("data.txt"); // bytes
filemtime("data.txt"); // last modified timestamp
is_readable("data.txt");
is_writable("data.txt");
// File operations
copy("src.txt", "dest.txt");
rename("old.txt", "new.txt");
unlink("delete.txt"); // delete file
mkdir("folder", 0755, true);
rmdir("folder");