- str_replace: documentation ( source)
<?php
$string = <<<EOT
etc etc etc content
[crowdpdf-total=field_585b0b3288d2e]
etc etc [crowdpdf-total=field_585b0b3288d2f]
etc content
EOT;
$replacements = [
'field_585b0b3288d2e'=> 864,
'field_585b0b3288d2f' => 987,
];
foreach ($replacements as $find => $replace) {
$string = str_replace("[crowdpdf-total=$find]", $replace, $string);
}
echo $string;