Sending a notification message to Telegram using its HTTP API via cURL

readme.md

1. Create a bot
2. Get the bot's API token from @BotFather
3. Add your bot to the chat you'll be sending messages to
4. Get the ID of the chat
   a. Fetch bot updates and look for the chat id:

   curl https://api.telegram.org/bot$TELEGRAM_BOT_TOKEN/getUpdates | -r '.result[].message.chat.id'

   b. OR, run bot.rb and @-mention your bot in the chat. The chat id will appear in bot.rb's output.
   The bot may need temporary message access: @BotFather > Bot Settings > Group Privacy > Turn off
5. Send a message using the HTTP API: https://core.telegram.org/bots/api#sendmessage

   curl -X POST \
        -H 'Content-Type: application/json' \
        -d '{"chat_id": "123456789", "text": "This is a test from curl", "disable_notification": true}' \
        https://api.telegram.org/bot$TELEGRAM_BOT_TOKEN/sendMessage

bot.rb

# Use this script to test that your Telegram bot works.
#
# Install the dependency
#
#   $ gem install telegram_bot
#
# Run the bot
#
#   $ ruby bot.rb
#
# Send a message to the bot to get the current chat's ID in the console output.
# If it's a group chat, invite them to the chat first.

require 'logger'
require 'telegram_bot'

TELEGRAM_BOT_TOKEN = "YOUR_BOT_API_TOKEN"

bot = TelegramBot.new(token: TELEGRAM_BOT_TOKEN, logger: Logger.new(STDOUT))

bot.get_updates(fail_silently: true) do |message|
  puts "@#{message.from.username}: #{message.text}"
  puts "Chat-ID: #{message.chat.id}"
end

Created a group, switching on themes\topics.
Got link for one topic (like this https://t.me/c/1234567890/1).
How to send message to this topic?