How to find correct locale name for CREATE DATABASE

I tried in Debian ("PostgreSQL 9.0.1 on x86_64-pc-linux-gnu, compiled by
GCC gcc-4.4.real (Debian 4.4.5-8) 4.4.5, 64-bit") :

1. CREATE DATABASE "mydb" WITH TEMPLATE=template0
LC_COLLATE='Estonian_Estonia.1257' LC_CTYPE='Estonian_Estonia.1257'
OWNER="mydb_owner" ENCODING='UNICODE'

2. CREATE DATABASE "mydb" WITH TEMPLATE=template0 LC_COLLATE='et_EE.UTF-8'
LC_CTYPE='et_EE.UTF-8' OWNER="mydb_owner" ENCODING='UNICODE'

3. 2. CREATE DATABASE "mydb" WITH TEMPLATE=template0
LC_COLLATE='et_EE.UTF8'
LC_CTYPE='et_EE.UTF8' OWNER="mydb_owner" ENCODING='UNICODE'

in all cases same error

invalid locale name

occurs.

Questions:

1. How to find correct locale name for Estonian in Debian Linux ?
In Windows case (1) works.

2. How to create portable CREATE DATABASE command for estonian locale which
works in all operating systems?

3. Or how to detect OS from PostgreSql server and select correct Estonian
locale ?

Andrus.