Where can I put a MEL file to show custom HUD every time Maya starts up?

I've written a MEL script, in ScriptEditor it works fine. I would like to save this MEL script in a .mel file for a custom Heads Up Display showing three translate parameters for selected geometry, and I want this HUD to appear in the Viewport every time Maya is loaded. I'm running Maya on Mac.

How can I do that?

headsUpDisplay -removePosition 0 1;

global proc float[] objectPosition() {
    string $selectedNodes[] = `selectedNodes`;
    float $position[3];
     
    if (size($selectedNodes) > 0) {
        string $mainObject = $selectedNodes[ (size($selectedNodes)-1) ];
        $position[0] = `getAttr $mainObject.translateX`;
        $position[1] = `getAttr $mainObject.translateY`;
        $position[2] = `getAttr $mainObject.translateZ`;
    } else {
        $position[0] = 0;
        $position[1] = 0;
        $position[2] = 0;
    }
    return $position;
}

headsUpDisplay 
    -section 0
    -block 1
    -label "Position:"
    -command "objectPosition()"
    -event "SelectionChanged"
    -nodeChanges "attributeChange"
    BrandNewHUD;

First approach

All I have to do is to create a file named userSetup.mel in the following directory:

• Mac OS: ~/Library/Preferences/Autodesk/maya/scripts
• Windows: \My Documents\maya\scripts
• Linux: ~/maya/scripts

I put there my MEL script. It shows my custom HUD whenever Maya starts up.

Second approach

Alternatively, I can insert my script inside initHUD.mel located in MacOS directory:

• /Applications/Autodesk/maya2020/Maya.app/Contents/scripts/startup/

But be careful! Make no mistakes there!