$re = '/<buffer name="[^"]*Lut[^"]*">.*?<\/buffer>/s';
$str = '<?xml version="1.0" encoding="utf-8"?>
<pimp xmlns:dt="urn:schemas-microsoft-com:datatypes">
<dllPath>C:\\ReplayCode\\Apps\\Pimp</dllPath>
<buffers>
<buffer name="InputMask">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
<buffer name="MaskErode">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
<buffer name="BlablaLutBla">
<width>256</width>
<height>256</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
<buffer name="MaskClose">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
<buffer name="2ndLutBlabla">
<width>256</width>
<height>256</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
<buffer name="InputVis">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>3</channels>
<type>IMG</type>
</buffer>
<buffer name="AddMaskEdge">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
<buffer name="EdgeVis">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>3</channels>
<type>IMG</type>
</buffer>
<buffer name="GrayEdge">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
<buffer name="EdgeMaskMulThreshold">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
<buffer name="MaskMulEdge">
<width>5120</width>
<height>3072</height>
<data>UCHAR</data>
<channels>1</channels>
<type>IMG</type>
</buffer>
</buffers> ';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php