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I'm looking for a way to edit HTML files from the command line similar to sed or awk, but using path expressions similar to jq or pup. In particular, newlines, white space and other formatting details shouldn't matter.

So I'd like to say something like "delete everything between <body> and first <p> tag following it, and replace it with the this text" or "replace every <b>...</b> with <p font-style=italic>...</p>, keeping the text in between". The rest of the document should remain unchanged.

A library for, say, Perl, Python or Haskell where I can do that easily with a few lines would also be fine (but I'd prefer a commandline tool).

Background: I want to use this to clean up lots of epub files with awkward formatting, bad language tags etc.

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    I use tidy to format html to one tag-per-line, and perl to process the tags. There are a few applications which do a more sophisticated job, but the majority have technical problems glossed over by their developers. Someone is certain to recommend one of those. – Thomas Dickey Mar 7 '17 at 9:11
  • Cleaning up formatting is one thing, and can be from the command line with utilities like js-beautify - which has a python script in its repo. or pandoc can do this. but to replace elements in a way which can handle unusual blank characters really needs a full HTML parser. I dont know of any way that you could limit the commands to one line shell statements either - you would need to write a script – the_velour_fog Mar 7 '17 at 9:42
  • @ThomasDickey: I'd like to avoid re-formatting to one tag per line, and even then I'd have to deal with stuff like nesting using Perl etc. – dirkt Mar 7 '17 at 11:05
  • xslt is the best too to do xml transformations, simple edits are possible with editors like ed, sed, vi however it can very quickly become unmanageable doing what would be simple in a transformation in what is intended as a text editor. – X Tian Mar 7 '17 at 16:38
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    redirect output to new file, if all is ok, then copy on top of original – X Tian Mar 7 '17 at 17:05
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I don't know of anything that would do what you want and it would be a lot of work to build something. For starters you'd have to build a compiler, using yacc or some such, to parse your commands and then pass them on to other code to actually do the transformations.

XLST might work but I doubt it. It's sitting on top of XML and HTML is too irregular a markup language to fit inside that rigid syntax: especially if you start dumping CSS on top of it.

I'd go with the Perl HTML::Parser library (or maybe one of its friends in the HTML module tree if they have a specialized tool for a common task of yours). It parses HTML documents into a little internal database tree and then you can manipulate that and dump it back out. I use it all the time to do things such as: get rid of all iframe tags and contents; get rid of all HTML tags but print out something close to the intended formatting in plaintext; and really complex screen scraper engines.

It's really simple to use and does all of the heavy lifting for you. See the CPAN page for examples. The distribution also comes with more examples to do things like strip out certain tags/elements and/or attributes.

Remember that back in the Stone Age Perl ruled the Web and was mostly concerned with slinging HTML around so the Perl Monks have been sharpening their HTML tools for decades now.

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