I think that if you qgis installed you will have also ogr2ogr (It's provided with the gdal-bin package). With the following command you will create a table called yousahpefile in your database:
ogr2ogr -f PostgreSQL PG:"host=server_ip user=username dbname=dbname password=password" yourshapefile.shp;
There are some workaroundssome workarounds if you find troubles with the encoding.