table size limit under Linux

I read that postgres table size is unlimited.
But, a postgres table is stored into a file, and the size of a file is
limited to approximately 2 Giga Bytes under Linux.

I tried to test this by inserting hundreds of thousands of rows into a table
: my insert queries failed when the file containing the table reached
approximately 2 Giga Bytes (under Linux).

So, it seems that the size of a Postgres table is limited to the maximum
file size under Linux (approximately 2 Giga Bytes).
Can anyone confirm that to me ?
If it is possible to have tables of unlimited size under Linux, can anyone
tell me how to do that ?

Thanks.