I don't have any plain debian systems to confirm with, as my boxen are generally ubuntu variants, but they don't typically stray TOO far from debian.
I assume the ngspice library is actually in /usr/local/lib , correct?
check the files/etc/ld.so.conf and if the directory exists, the files inside /etc/ld.so.conf.d/
One of these files should contain the line
/usr/local/lib
If none of the files include the line, add it to /etc/ld.so.conf
(or read the man page for ldconfig for how to properly add it to a file inside /etc/ld.so.conf.d/ )
run?
sudo ldconfig
The program ought to be able to find it then.
