Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Helper/Sample.php
public function getTemporaryFilename($extension = 'xlsx')
    {
        $temporaryFilename = tempnam($this->getTemporaryFolder(), 'phpspreadsheet-');
        unlink($temporaryFilename);

        return $temporaryFilename . '.' . $extension;
    }
public function getTemporaryFilename($extension = 'xlsx')
    {
        $temporaryFilename = tempnam($this->getTemporaryFolder(), 'phpspreadsheet-');
        unlink($temporaryFilename);

        return $temporaryFilename . '.' . $extension;
    }
Return a random temporary file name.

@param string $extension

@return string