A list of supported locales is available at /usr/share/i18n/SUPPORTED

See a full list with:

> cat /usr/share/i18n/SUPPORTED

Take the first portion to generate full locale information for a region:

> locale-gen ru_RU.UTF-8

Then use this for the current shell session with

> LANG=ru_RU.utf8

Expand this to the entire system with: 

> export LANG=ru_RU.utf8

You can make this permanent for one user by adding this line to the ~/.profile or ~/.bashrc.

Make it permanent for the entire system by editing:

> sudo vim /etc/defaults/locale

# Variables

While generally set together, the variables setable are:

| Variable      | Description |
|:-------------:|:------------|
| LC_TIME | Date and time |
| LC_NUMERIC | Nonmonetary numeric formats |
| LC_PAPER | A4 vs wrong paper |
| LC_ADDRESS | Address formats, for those amazingly concise Polish addresses. |
| LC_TELEPHONE | Telephone number formats. |
| LC_MEASUREMENT | Metric or Imperial, but no Impetric available. |
| LC_IDENTIFICATION | Metadata about the locale information |
| LC_ALL | Just everything at once. |