If you just installed postgresql 8.x/9.x and it has never asked you to create a superuser/password here is how to reset the default superuser and its password:
sudo -u postgres psql postgres
# \password postgres
Enter new password:
If you just installed postgresql 8.x/9.x and it has never asked you to create a superuser/password here is how to reset the default superuser and its password:
sudo -u postgres psql postgres
# \password postgres
Enter new password: