Garry's Mod Addon Creator and Extractor
gmad <command> <options>
To create a new .gma file
gmad.exe create -folder "C:\path\to\addon\folder\" -out "C:\where\to\save\file\out.gma"
To extract an existing .gma file into its parent folder
gmad.exe extract -file "C:\steam\etc\garrysmod\addons\my_addon_12345.gma"
To extract an existing .gma file into another folder
gmad.exe extract -file "C:\steam\etc\garrysmod\addons\my_addon_12345.gma" -out "C:\this\folder"
Compiling requires Bootil
https://github.com/garrynewman/bootil
You can either add the lib and include folder to your path, or copy all the files in, or set them on the premake command line..
premake4 --outdir="bin/" --bootil_lib="c:/bootil/lib/" --bootil_inc="c:/bootil/include/" vs2010
Or on linux
premake4 --outdir="bin/" --bootil_lib="/whatevs/bootil/lib/" --bootil_inc="/whatevs/bootil/include/" gmake