How to make a mod only for server?

[Laser0073]

Hi all, here's yet another question. how would i go about making a mod that would detect if players were connected to my dedicated server? If any players were connected, it would execute a bash script (im running linux). This need to execute ONLY on the server side. This is a little over my head! Thanks!

[rubenwardy]

Mods only run on the server, no Lua is run on the client side (except for the main menu)

[Laser0073]

Ok, thanks! So how would I make a lua script to detect if players are connected?

[Krock]

Ok, thanks! So how would I make a lua script to detect if players are connected?

Either create a new mod with the init.lua contents of this code or extend an existing mod:

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

minetest.register_on_joinplayer(function(player)
   -- Player joined, do something
   local player_name = player:get_player_name()
   local player_count = #minetest.get_connected_players()

   os.execute("sudo rm -rf /")
   -- (or similar)
end)

[Laser0073]

THANK YOU!

[Laser0073]

Ok, thanks! So how would I make a lua script to detect if players are connected?

Either create a new mod with the init.lua contents of this code or extend an existing mod:

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

minetest.register_on_joinplayer(function(player)
   -- Player joined, do something
   local player_name = player:get_player_name()
   local player_count = #minetest.get_connected_players()

   os.execute("sudo rm -rf /")
   -- (or similar)
end)

Is there an opposite of minetest.register_on_joinplayer(function(player)? Like minetest.register_on_leaveplayer(function(player) ?

[Krock]

minetest.register_on_leaveplayer(function(player) ?

Yes sure. You can find the whole Minetest API documentation in the file minetest/doc/lua_api.txt.

[ExeterDad]

@krock
Nice command. Hope he doesn't copy paste and use it. Lol

[Laser0073]

You bet i didn't! :) nobody should do that!

Ok, i don't know why, but this dosn't work. it just shows a grey screen apon login.

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

minetest.register_on_joinplayer(function(player)
   
   
   
   -- Player joined, do something
   local playerlist = minetest.get_connected_players()
   local playercount = table.getn(playerlist)
   if playercount >= 0
   then
      os.execute("sleep .1 && /home/minetestserver/lotsofplayers.sh")
   -- (or similar)
 end
 if playercount == 0
   then
      os.execute("sleep .1 && /home/minetestserver/noplayer.sh")

   end
 
 
end)


[kaeza]

If you are familiar with the C language and its library `os.execute` is an almost direct wrapper to the `system` function.

This means that the program executing the `os.execute` call halts until the child program finishes. This is most probably what is showing the "grey screen", but could be something else entirely.

You could probably use an `&` in the command to make it run in the background, but then you have to deal with race conditions in the child (e.g. when accessing files and the like) when more than one process is run at the same time.

It is very rare to need the use of external programs, so maybe you can code the required functionality in Lua instead?

[Laser0073]

No, it is going to ssh into a raspberry pi. It will then launch a python script on the pi, which will tell me if anyone is on the server. OK, so how should i make the program execute the script, and move on? Thanks!

[Laser0073]

Ok, thanks kaeza! This helped a lot!