Is publishing a book summary online or distributing it to acquaintances for their benefit considered a violation of copyright and forbidden?

There is no objection to summarizing the idea of a book and publishing it electronically or in print without the author's permission. A summary is not the book itself, and the researcher's effort in it does not require permission. Scientific utilization through summarization and quotation is permissible শরعاً (religiously/legally) and does not require the author's permission. Rather, what is required is attributing statements to their sources, especially if the quotation is verbatim.