epub-cover command-line tool
epub-cover tool extract cover image from EPUB book.
% epub-cover --help Extract cover image. Image is put to current directory with the same name in EPUB. It is put to specified directory when `--output' option is given. Usage: epub-cover [options] EPUBFILE Options: -o, --output=DIR Directory to put image file
% epub-cover childrens-literature.epub Cover image output to cover.png
As output indicates, cover image file is output to current directory. The file name is the same to one in EPUB file.
You can specify a directory to output the cover file by
% epub-cover --output=/tmp childrens-literature.epub Cover image output to /tmp/cover.png
Extract from the web
epub-open accepts URI instead of file path.
% epub-cover https://raw.githubusercontent.com/IDPF/epub3-samples/master/30/page-blanche/ Cover image output to cover.jpg