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 workarounds][1] if you find troubles with the encoding.


  [1]: http://stackoverflow.com/questions/1377662/encoding-problems-with-ogr2ogr-and-postgis-postgresql-database