Tail file and send lines to Telegram

teletail

#!/bin/bash

# https://stackoverflow.com/a/48779000
# https://dev.to/nathannosudo/bash-script-to-send-a-message-in-telegram-from-your-terminal-20c7

if [ "$#" -ne 1 ]; then
    echo "Usage: API_TOKEN=123 CHAT_ID=456 teletail /var/log/test.log"
    exit 0
fi

if [ ! -f "$1" ]; then
    echo "File $1 not found!"
    exit 1
fi

process_new_line() {
    local var="" #declare some local variables here 
    read
    while true
    do
        #process $REPLY 
        #The new line content is in the variable $REPLY 
        #store the result in the local variable according to your rules.
        curl -s -X POST https://api.telegram.org/bot$API_TOKEN/sendMessage -d chat_id=$CHAT_ID -d text="$REPLY"
        read
    done
}

tail -n0 -f "$1" | process_new_line

systemd service example:

[Service]
ExecStart=/usr/local/bin/teletail /var/log/test.log
Restart=always
User=www-data
Group=www-data

Environment=API_TOKEN=123
Environment=CHAT_ID=123

[Install]
WantedBy=multi-user.target