[eschwartz]

Kovid changed --for-machine to use JSON output. Since then, I have taken a look at this, and came up with the following.

Requirements -- the command-line tool "jshon" for parsing json. (We could probably work something out with awk/sed, but let's use an actual json tool, why don't we. Much easier.)

So let's go ahead and

sudo apt-get install jshon

#!/bin/bash

# Save path for JSON list
librarylog=/tmp/library-list.json
# Generate JSON of library formats
calibredb list -s "not formats:\"=EPUB\"" --for-machine -f formats > $librarylog
echo "finished saving list of books"
# How many books do we have
number_of_books=$(jshon -l < $librarylog)

## Let's do the conversion
# Loop through all indices of the booklist
for ((i=0;i<=number_of_books-1;i++)); do
    # Where is the book.FMT
    bookpath=$(jshon -e $i -e "formats" -e 0 -u < $librarylog)
    # Convert to EPUB and leave in current dir
    ebook-convert "$bookpath" ".epub"
done

Either run this from the directory all the books should go in, or add
cd /path/to/savedir
to the code.

We can give the code acrobatics, and save the format to calibre using the following for loop instead:

    # What is the book's id #
    book_id=$(jshon -e $i -e "id" -u < $librarylog)
    # Where is the book.FMT
    bookpath=$(jshon -e $i -e "formats" -e 0 -u < $librarylog)
    # convert to EPUB  and save to temp
    ebook-convert "$bookpath" "/tmp/${book_id}.epub"
    # Add new format to calibre book record
    calibredb add_format "$book_id" "/tmp/${book_id}.epub"