Add Package Control in Sublime Text 3 through the command line

The easiest way is to download https://packagecontrol.io/Package%20Control.sublime-package using wget or curl, and store it in ~/.config/sublime-text-3/Installed Packages. It will then set itself up upon first starting the editor. As a bonus, if you create ~/.config/sublime-text-3/Packages/User/Package Control.sublime-settings and populate it with the packages you want installed, everything should work more-or-less automatically to download and install everything. A restart is generally a good idea, but this is a good way to script the setup of a new development environment. As an example, a minimal ST3 Package Control.sublime-settings file is below, so you can get an idea of how it’s set up:

{
    "installed_packages":
    [
        "AutoFileName",
        "BracketHighlighter",
        "ExportHtml",
        "GenerateUUID",
        "HexViewer",
        "Neon Color Scheme",
        "PackageResourceViewer",
        "PlistJsonConverter",
        "Python Flake8 Lint",
        "Python Improved",
        "SideBarEnhancements",
        "SideBarGit",
        "SublimeCodeIntel",
        "SublimeREPL",
        "Tag",
        "Terminal",
        "Theme - Soda"
    ]
}

Good luck!