ob_get_flush — Flush the output buffer, return it as a string and turn off output buffering
ob_get_flush(): string|false
ob_get_flush() flushes the output buffer, return it as a string and turns off output buffering.
Example of ob_get_flush
<?php
//using output_buffering=On
print_r(ob_list_handlers());
//save buffer in a file
$buffer = ob_get_flush();
file_put_contents('buffer.txt', $buffer);
print_r(ob_list_handlers());
?>