Write content to file in Magento2

$om = MagentoFrameworkAppObjectManager::getInstance();

$filesystem = $om->get(‘MagentoFrameworkFilesystem’);

$directoryList = $om->get(‘MagentoFrameworkAppFilesystemDirectoryList’);

$varDirectory = $filesystem->getDirectoryWrite($directoryList::VAR_DIR);

$varPath = $directoryList->getPath(‘var’);

$fileName = ‘demo.txt’;

$path = $varPath . ‘/custom/’ . $fileName;

$error = [];

$contents = print_r($error, true);

$varDirectory->writeFile($path, $contents);