Hi Peter,
I have created the base by using the command osm2pgsql ( i have downloaded the file tunisia.osm ) and the operation had been termined without any error.
So I obtained the following tables : planet_osm_line; planet_osm_point; planet_osm_polygon; planet_osm_roads.
Concerning the loging operation from the command line, yes i am able to log and sett the data.
Concerning the osm.xml file, when i type the following command
source set-mapnik-env
./customize-mapnik-map >$MAPNIK_MAP_FILE
./z0_generate_tiles.py
the file osm.xml is configured with the right parameters ( the name of the base, the user, the password )
So, what you suggest for me ? thanks in advance 
Ahmed