# Debian locale and timezone

Configure language, character encoding, and time settings for your system.

## Timezone

Show current timezone:

```bash
timedatectl
```

List available timezones:

```bash
timedatectl list-timezones
timedatectl list-timezones | grep America
```

Set timezone:

```bash
sudo timedatectl set-timezone America/New_York
sudo timedatectl set-timezone Europe/London
sudo timedatectl set-timezone UTC
```

Or manually:

```bash
sudo ln -sf /usr/share/zoneinfo/America/New_York /etc/localtime
```

Check timezone file:

```bash
cat /etc/timezone
```

## System time

Enable network time sync (NTP):

```bash
sudo timedatectl set-ntp true
```

Show sync status:

```bash
timedatectl
```

Manually set time:

```bash
sudo timedatectl set-time "2024-01-15 14:30:00"
```

## Locale

Show current locale:

```bash
locale
```

List available locales:

```bash
locale -a
```

Set system locale:

```bash
sudo update-locale LANG=en_US.UTF-8
sudo update-locale LC_TIME=en_GB.UTF-8
```

Reconfigure locales:

```bash
sudo dpkg-reconfigure locales
```

Then select locales to generate. Changes take effect after logout/login.

## Keyboard layout

Show current:

```bash
setxkbmap -query
```

Set temporarily:

```bash
sudo loadkeys us
```

Persistent configuration:

```bash
sudo dpkg-reconfigure keyboard-configuration
```

Then restart:

```bash
sudo systemctl restart keyboard-setup
```

## Locale categories

- `LANG`: default language
- `LC_TIME`: date/time format
- `LC_NUMERIC`: number format (. vs ,)
- `LC_MONETARY`: currency symbols
- `LC_COLLATE`: sorting order
- `LC_CTYPE`: character classification
- `LC_MESSAGES`: error messages
- `LC_PAPER`: paper size (A4, Letter)

Each can be set independently:

```bash
export LC_TIME=de_DE.UTF-8
date           # shows German date format
```

## Common locales

- `en_US.UTF-8`: US English, UTF-8
- `en_GB.UTF-8`: British English
- `de_DE.UTF-8`: German
- `fr_FR.UTF-8`: French
- `ja_JP.UTF-8`: Japanese
- `C.UTF-8`: POSIX locale (useful for scripts)

Most modern systems use UTF-8; avoid older encodings (ISO-8859-1, etc.).

## Tips

- Servers usually use `C.UTF-8` or `en_US.UTF-8`
- Locale affects sorting in `ls`, collation in databases
- Always set locale before user environment to avoid surprises