How to identify a bot by User-agent?

Question

PHP

How to identify a bot by User-agent?
Pen is interested in any bots - search engines, from social networks, in short - not real people.
How to determine them by User-Agent?
Let's say they don't change the User-agent to "normal".
if anything - I need to sort the logs

Answer 1

How to determine that the search bot and not a person?

Answer 2

So far I have this code:

if(strlen($useragent)<75){
  $isbot = 'BOT';
}else if(strlen($useragent)>100){
  $isbot = 'USER';
}else{
  $isbot = 'ХЗ, '.strlen($useragent);
}

Answer 3

You can reliably determine only by IP or you need to connect JavaScript and watch the behavior

Answer 4

well, in their user agent it is written what kind of bot they are, take it and sort it

Answer 5

Implementation with a small function in php
https://youtu.be/Dz-eDdHs4m8