CREATE FUNCTION st_Box2d_in(cstring) RETURNS Box2d
    AS '$libdir/liblwgeom','Box2DFLOAT4_in'
    LANGUAGE c IMMUTABLE STRICT;

产生错误

could not access file "$libdir/liblwgeom": No such file or directory

而

CREATE FUNCTION st_Box2d_in(cstring) RETURNS Box2d
    AS '/usr/local/pgsql/lib/liblwgeom','Box2DFLOAT4_in'
    LANGUAGE c IMMUTABLE STRICT;

正常工作

的输出

% pg_config --pkglibdir
/usr/local/pgsql/lib

似乎是正确的.