Trying to get players SteamID and write it to a txt file

[The French Spy]

Hello, i'm trying to get the SteamID of players who connect to the server and write it followed by a comma in a file called by the player's SteamID.txt but I get an error from the
console
[ERROR] lua/autorun/data.lua:8: attempt to index a string value with bad key ('Write' is not part of the string library)
  1. error - [C]:-1
   2. __index - lua/includes/extensions/string.lua:297
    3. v - lua/autorun/data.lua:8
     4. unknown - lua/includes/modules/hook.lua:84
Here is my code
if file.Exists( "characters", "DATA" ) == false then
    file.CreateDir( "characters" )
end

hook.Add( "PlayerInitialSpawn", "Spawn", function( player )
    steamid = player:SteamID()
    file = steamid..".txt"
    file.Write( "characters/"..steamid..".txt", steamid.."," )
end )

[nellsn]

1. Use local when using variables (This will explain: Programming in Lua)
2. Don't use variables names that are used as a global GMod library (such as: file, player, etc.) Especially when they are not set as local....
3. Use Player/SteamID64 instead of just SteamID

[The French Spy]

thanks, I didn't saw that I forgot the local before the variables :/