Retrieve the lines in a file in random order without repeating the lines or loading the file into memory first.

randomLineGenerator

function getLinesInRandomOrder($filePath)
{
    $file = new SplFileObject($filePath);
    $file->setFlags(SplFileObject::DROP_NEW_LINE | SplFileObject::SKIP_EMPTY);
    $file->seek(PHP_INT_MAX);
    $linesToTry = range(0, $file->key());
    shuffle($linesToTry);
    foreach ($linesToTry as $line) {
        $file->seek($line);
        yield $file->current();
    }
}