When I do the following in a windows cmd box:
Code:
calibredb list -f id --search "date:<10daysago"
I get a newline-separated list of ids.
Example output:
Code:
id
50
208
209
1059
1060
1062
What exactly are you getting?
If you are trying to get rid of the first line (id) then
see the solutions in this post.
What version of calibre are you running?