Problem with .pgpass

Hi here,

I'm trying to make my dump script working but it is not.

I tried to put my password in a .pgpass file into the home directory of the root user (so /root/.pgpass). Here is a cat of that file :
*:*:*:*:test

(I tried only with stars to be sure my rule was not too strict).

So, il I try this command :

root@pc:~ # psql -h localhost -U postgres

I get :

psql: FATAL:  authentification par mot de passe échouée pour l'utilisateur  « postgres »

(this is in french but it means that the password authentication method failed for the user 'postgres')

If I rename my .pgpass into .pgpass.old, I can log in to postgres with the same command :

root@pc:~ # psql -h localhost -U postgres

When prompt for a password, I enter 'test' and it's working ...

Someone understand where's the problem?