telegram-bot-bash/doc/4_expert.md

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## Expert Use

### Handling UTF-8 character sets
UTF-8 is a variable length encoding of Unicode. UTF-8 is recommended as the default encoding in JSON, XML and HTML, also Telegram make use of it.

The first 128 characters are regular ASCII, so it's a superset of and compatible with ASCII environments. The next 1,920 characters need
two bytes for encoding and covers almost all ```Latin``` alphabets, also ```Greek```, ```Cyrillic```,
```Hebrew```, ```Arabic``` and more. See [Wikipedia](https://en.wikipedia.org/wiki/UTF-8) for more details.

#### Setting up your Environment
In general ```bash``` and ```GNU``` utitities are UTF-8 aware if you to setup your environment
and your scripts accordingly:

1. Your Terminal and Editor must support UTF-8:
   Set Terminal and Editor locale to UTF-8, eg. in ```Settings/Configuration``` select UTF-8 (Unicode) as Charset.

2. Set ```Shell``` environment to UTF-8 in your  ```.profile``` and your scripts. The usual settings are:

```bash
export 'LC_ALL=C.UTF-8'
export 'LANG=C.UTF-8'
export 'LANGUAGE=C.UTF-8'
```
   If you use other languages, eg. german or US english, change the shell settings to:
```bash
export 'LC_ALL=de_DE.UTF-8'
export 'LANG=de_DE.UTF-8'
export 'LANGUAGE=de_DE.UTF-8'
```
```bash
export 'LC_ALL=en_US.UTF-8'
export 'LANG=de_en_US.UTF-8'
export 'LANGUAGE=den_US.UTF-8'
```
3. make shure your bot scripts use the correct  settings, eg. include the lines above at the beginning of your scripts

To display all availible locales on your system run ```locale -a | more```. [Gentoo Wiki](https://wiki.gentoo.org/wiki/UTF-8)

#### Bashbot UTF-8 Support
Bashbot handles all messages transparently, regardless of the charset in use. The only exception is when converting from JSON data to strings.

Telegram use JSON to send / recieve data. JSON encodes strings as follow: Characters not ASCII *(>127)* are escaped as sequences of ```\uxxxx``` to be regular ASCII. In addition multibyte characters, *e.g. Emoticons or Arabic characters*, are send in double byte UTF-16 notation.
The Emoticons ``` 😁 😘 ❤️ 😊 👍 ``` are encoded as: ``` \uD83D\uDE01 \uD83D\uDE18 \u2764\uFE0F \uD83D\uDE0A \uD83D\uDC4D ```

**This "mixed" JSON encoding needs special handling and can not decoded from** ```echo -e``` or ```printf '%s\\n'```

Most complete support for decoding of multibyte characters can only be provided if python is installed on your system.
**Without phyton bashbot falls back to an internal, pure bash implementation which may not work for some corner cases**.


### Run as other user or system service
Bashbot is desingned to run manually by the user who installed it. Nevertheless it's possible to run it by an other user-ID, as a system service or sceduled from cron. This is onyl recommended for experiend linux users.

Setup the environment for the user you want to run bashbot and enter desired username, e.g. nobody :
```bash
sudo ./bashbot.sh init
```

Edit the file ```bashbot.rc``` and edit the following lines to fit your configuration:
```bash
#######################
# Configuration Section

# edit the next line to fit the user you want to run bashbot, e.g. nobody:
runas="nobody" 

# uncomment one of the following lines 
# runcmd="su $runas -s /bin/bash -c "      # runasuser with su
# runcmd="runuser $runas -s /bin/bash -c " # runasuser with runuser

# edit the values of the following lines to fit your config:
start="/usr/local/telegram-bot-bash/bashbot.sh"	# location of your bashbot.sh script
name=''   # your bot name as given to botfather, e.g. mysomething_bot

# END Configuration
#######################
```
From now on use 'bashbot.rc' to manage your bot: 
```bash
sudo ./bashbot.rc start
```
Type ```ps -ef | grep bashbot``` to verify your Bot is running as the desired user.

If your  Bot is started by 'bashbot.rc', you must use 'bashbot.rc' also to manage your Bot! The following commands are availible:
```bash
sudo ./bashbot.rc start
sudo ./bashbot.rc stop
sudo ./bashbot.rc status
sudo ./bashbot.rc suspendback
sudo ./bashbot.rc resumeback
sudo ./bashbot.rc killback
```
To change back the environment to your user-ID run ```sudo ./bashbot.sh init``` again and enter your user name.

To use bashbot as a system servive include a working ```bashbot.rc``` in your init system (systemd, /etc/init.d).

### Scedule bashbot from Cron
An example crontab is provided in ```examples/bashbot.cron```.

- If you are running bashbot with your user-ID, copy the examples lines to your crontab and remove username ```nobody```.
- if you run bashbot as an other user or a system service edit ```examples/bashbot.cron``` to fit your needs and replace username```nobody``` with the username you want to run bashbot. copy the modified file to ```/etc/cron.d/bashbot```

#### [Prev Expert Use](4_expert.md)
#### [Next Best Practice](5_practice.md)

#### $$VERSION$$ v0.72-0-ge899420