用于preg_replace HTML注释的正则表达式和SVG文件中的空标记

Question

When Illustrator exports SVG files, it doesn't do a very good job of optimizing them. One annoying and pointless thing it puts in near the top of the file is the following HTML comment:

<!-- Generator: Adobe Illustrator 17.1.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->

I also have multiple empty group tags with ids like so:

<g id="svgSteps">
</g>
<g id="svgBase">
</g>

Now, I'm trying to write some PHP using regex and preg_replace to remove things like this. I'm completely new to regex and already tried some solutions posted on stackoverflow which didn't work for me.

For the HTML comments I tried:

$fileContent = file_get_contents('my_file');
$fileContent = preg_replace('/<!--(.|\s)*?-->/','',$fileContent);
file_put_contents('my_file',$fileContent);

Which didn't work. When I tried a str_replace for <!-- instead, that worked so I know the file_get_contents and file_put_contents are working (no issues with permissions).

What would be the correct regex for:

1. Finding HTML comments starting with <!-- and ending with --> that have whitespace, alpha-numeric characters, periods, commas, colons and brackets inside.

2. Finding tags starting with <g and ending with </g> that can have an id but only have either whitespace or nothing inside the tag.

Answer 1

try

    preg_replace("/((<g id=\".*\">)|(<g>))[\s]*(<\/g>)/",'',$fileContent)
    preg_replace("/(<!--)[\s\S]*(-->)/",'',$fileContent)