How to repack an epub file from command line

Question

I unzipped an epub file to make some minor modifications. How can I repack it properly to be a valid epub file from command line on Linux?

Answer 1

zip -rX ../my.epub mimetype META-INF/ OEBPS/

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Without -X you could get the following when validating it with EpubCheck:

ERROR: my.epub: Mimetype entry must not have an extra field in its ZIP header

If mimetype is not the first in the epub file EpubCheck prints the following:

ERROR: my.epub: Mimetype entry missing or not the first in archive

Answer 2

zip -X0 "my.epub" "mimetype"
zip -Xr "my.epub" "META-INF/" "OEBPS/"

As palacsint already pointed out, without the -X flag, one would run into the epubcheck error PKG_005

"The mimetype file has an extra field of length %1$s. The use of the extra field feature of the ZIP format is not permitted for the mimetype file."

because the mimetype file is being used as magical number within the compressed zip file, and the zip extra field feature (where zip programs and operating systems can place non-standardized data) would destroy the magical number mechanism (see https://github.com/IDPF/epubcheck/pull/497). The -0 flag makes sure that the mimetype file doesn't get compressed, which is also necessary for the mimetype file to work as a magical number, otherwise the data at the position where the mimetype file is expected could be compressed, scrambled gibberish.

Answer 3

A one-liner based on the previous answers, which will take the current dirname as the epub name, and the contents of the current dir as the epub: zip -rX "../$(basename "$(realpath .)").epub" mimetype $(ls|xargs echo|sed 's/mimetype//g')

Answer 4

I'm using this python script to batch repackage the files.

import os
import shutil
import zipfile

# Enter the paths
path_to_files = "/Users/matteo/Desktop/ebooks"   # Path to directory containing epub packages
path_to_new_files = "/Users/matteo/Desktop/ebooks_conv"   # Path to store new epub files in

# Function to store all filenames in a list
def extract_filename(path_to_files):
    filenames = []
    for f in os.listdir(path_to_files):
        f_name, f_ext = os.path.splitext(f)
        if f_ext == ".epub":
            filenames.append(f_name)
    filenames.sort()
    return filenames

# Function to generate new epub files
def create_epub(filenames, path_to_files, path_to_new_files):
    total_files = len(filenames)
    for i, filename in enumerate(filenames, 1):
        epub_path = os.path.join(path_to_files, filename + ".epub")
        
        # Remove iTunesMetadata.plist if exists
        plist_path = os.path.join(path_to_files, "iTunesMetadata.plist")
        if os.path.exists(plist_path):
            os.remove(plist_path)
        
        # Copy the EPUB files to a temporary directory to avoid zipping recursively
        temp_dir = os.path.join(path_to_new_files, filename)
        shutil.copytree(epub_path, temp_dir)
        
        # Create the new EPUB archive
        with zipfile.ZipFile(os.path.join(path_to_new_files, filename + ".epub"), 'w') as new_epub:
            for root, dirs, files in os.walk(temp_dir):
                for file in files:
                    file_path = os.path.join(root, file)
                    # Write each file to the archive
                    new_epub.write(file_path, os.path.relpath(file_path, temp_dir))
        
        # Clean up the temporary directory
        shutil.rmtree(temp_dir)
        
        print("File #", i, " has been processed successfully. Remaining files:", total_files - i)

filenames = extract_filename(path_to_files)
create_epub(filenames, path_to_files, path_to_new_files)