Some epub readers ignore HR element in HTML. This program fixes it by replacing all HRs with '* * *'.

hr_replace_for_epub.py

#! /usr/bin/env python
# -*- coding:utf-8 -*-

"""Some epub readers ignore HR element in HTML. This program fixes it by replacing all HRs with '* * *'. (Replacement is actually customizable beyond that)"""

import sys
import argparse
from ebooklib import epub
import re
import os


if __name__ == '__main__':

    parser = argparse.ArgumentParser()
    parser.add_argument('-v', '--verbose', action='store_true',
                        default=False,
                        help='turn on verbose message output')
    parser.add_argument('-O', '--overwrite', action='store_true',
                        default=False)
    parser.add_argument('-n', '--dryrun', action='store_true',
                        default=False)
    parser.add_argument('-c', '--context', type=int,
                        default=20)
    parser.add_argument('-p', '--pattern', type=str,
                        default='<hr.*?>')
    parser.add_argument('-r', '--replace', type=str,
                        default='<p style="text-align: center;">* * *</p>')
    parser.add_argument('files', nargs='+')
    args = parser.parse_args()
    if args.verbose:
        sys.stderr.write("%s\n" % args)

    hrpat = re.compile(args.pattern, re.IGNORECASE)
    
    for fname in args.files:
        book = epub.read_epub(fname)
        changed = False

        def repl(m):
            if args.verbose:
                print(fname, item.content[m.start()-args.context:m.end()+args.context])
            return args.replace
        
        for item in book.get_items():
            if isinstance(item, epub.EpubHtml):
                newcontent = re.sub(hrpat, repl, item.content)
                if newcontent != item.content:
                    item.content = newcontent
                    changed = True

        if changed:
            if args.overwrite:
                newname = fname
            else:
                base, ext = os.path.splitext(fname)
                newname = base + '_fixed' + ext
            if not args.dryrun:
                epub.write_epub(newname, book, {})
            print(newname)