Hi
I made a small shell script to search all my libraries at one go (which is not possible in the gui as far as I know)
I hope it is useful to you as well.
Code:
#!/bin/bash
DATABASE=()
DATABASE=("path_to_database_1" "path_to_database_2" "path_to_database_3")
echo ${DATABASE[*]}
for a in ${DATABASE[*]}; do
echo $a
calibredb list --library-path=$a -s $*
done;
Then in the shell just type the name of the script and yur search query. It will list all the found books according to their respective lib.
I do not know how to make this into a plugin. it would be nice if it could be invoked inside the gui.