Garry's Mod Lua Scripting

Garry's Mod Guide • Updated Jan 19, 2026

Garry's Mod Lua Scripting Guide

Introduction to Lua scripting for creating custom server functionality and game modes.

Understanding Lua in GMod

Garry's Mod uses Lua as its scripting language. Scripts run in different realms:

Server: Runs on server, handles game logic
Client: Runs on player's computer, handles UI/rendering
Shared: Runs on both server and client

Script Locations

garrysmod/lua/autorun/server/    # Server-side scripts
garrysmod/lua/autorun/client/    # Client-side scripts
garrysmod/lua/autorun/           # Shared scripts
garrysmod/lua/gamemodes/         # Game mode scripts
garrysmod/lua/weapons/           # Custom weapons
garrysmod/lua/entities/          # Custom entities
        

Basic Script Structure

-- Comments start with --

print("Hello, GMod!")

local playerName = "Player"
local playerHealth = 100

function GreetPlayer()
    print("Welcome, " .. playerName)
end

GreetPlayer()
        

Common Hooks

Hooks allow you to run code at specific events:

-- Server-side hook
hook.Add("PlayerSpawn", "MySpawnHook", function(ply)
    print(ply:Nick() .. " has spawned!")
    ply:SetHealth(150)
end)

-- Shared hook
hook.Add("Think", "MyThinkHook", function()
    -- Runs every frame
end)
        

Essential Functions

-- Print to console
print("Message")

-- Send message to player
ply:ChatPrint("Hello!")

-- Send message to all players
for k, v in ipairs(player.GetAll()) do
    v:ChatPrint("Server Message")
end

-- Create entity
local ent = ents.Create("prop_physics")
ent:SetPos(Vector(0, 0, 0))
ent:Spawn()
        

Creating a Simple Command

hook.Add("PlayerSay", "MyCommandHook", function(ply, text)
    if text == "!health" then
        ply:SetHealth(100)
        ply:ChatPrint("Health restored!")
        return "" -- Prevent message from showing
    end
end)
        

Working with Players

-- Get all players
local players = player.GetAll()

-- Iterate through players
for k, ply in ipairs(players) do
    print(ply:Nick(), ply:SteamID(), ply:GetHealth())
end

-- Find player by name
local target = player.GetByName("PlayerName")

-- Check if player is admin
if ply:IsAdmin() then
    -- Admin-only code
end
        

Best Practices

Use local variables for performance
Add comments to complex code
Test scripts on a local server first
Use print() for debugging
Avoid expensive operations in Think hooks
Clean up entities when no longer needed

Resource: Check the GMod Wiki for complete API documentation.

Learning More

Official GMod Wiki
Facepunch Forums
Explore existing addons for examples

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