How do I find out which font is chosen by gnuplot when only specifying family?

Question

I'm using the pngcairo terminal within gnuplot to produce images. Font is set to "sans,9" when specifying the terminal. How can I tell which specific font was picked for rendering?

terminal command: set terminal pngcairo font "sans,9" size 1500,1000

(edit) More info: Installed under Windows 7 OS. I just need to find what font was used for the given statement in gnuplot 4.4.4, which was used to create many plots. gnuplot 4.6.0 decides on a different font for the same statement, and it would be practically impossible to re-render all earlier plots to match.

Answer 1

I created a file test.gp

set terminal pngcairo font "sans,9" size 1500,1000
set output "test.png"
plot sin(x)

Run gnuplot under strace

strace -o st.out gnuplot test.gp

grep

grep 'open.*/usr/share/font.*' st.out 

gives me (Linux 3.0.0-22-generic #36-Ubuntu)

open("/usr/share/fonts/truetype/ttf-dejavu/DejaVuSans.ttf", O_RDONLY) = 5