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I want to remove comment tags in an html file.

<!--- <script save and execute me> -->

must become:

<script save and execute me>

I tried 

sed -i s_^<!-- \(.*\) -->$_\1_ text.sed

but that fails because the < and > are considered to be read in/out characters. I than tried:

sed -i 's_^<!-- \(.*\) -->$_\1_' text.sed

but than the \1 is not evaluated as it should. Hopefully somebody here has ideas?

regards, Jeroen.

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1 Answer

up vote 2 down vote accepted

Given a file, test.html, containing:

<html>
<!--- <script save and execute me> -->
</html>

The command:

sed -e "s/<!---* *<\(.*\)> *-->/<\1>/" test.html

emits:

<html>
<script save and execute me>
</html>

Be aware that this would also transform:

<html>
<!-- some info explaining why we have commented out the following -->
<!-- <hr> -->
<!--- <script save and execute me> -->
</html>

into:

<html>
<!-- some info explaining why we have commented out the following -->
<hr>
<script save and execute me>
</html>
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1  
This (and every other attempt to parse HTML with sed) will fail spectacularly in so many different ways. I can count at least three different ways at a glance to make this fail. Regex is not for parsing HTML – Darth Android Jul 7 '11 at 19:33
3  
The question wasn't about parsing HTML, it was about making a specific substitution in a file. The answer above isn't intended to do any more than solve the one specific problem. As far as it goes, SED is a fine tool for solving specific problems like this where the form of the input is clearly understood, regardless of the context. – BillP3rd Jul 7 '11 at 19:46
Added additional example illustrating possible unintended consequences alluded to by @Darth Android. – BillP3rd Jul 7 '11 at 19:57
@BillP3rd, thank you for your patience and your response to Darth Android. I'm more than aware that regex is not for parsing html but as you argued this is a very specific usecase for commenting out script references to local js files, and commenting in references to external js google api's – dr jerry Jul 7 '11 at 21:29

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