Linux USB: turning the power on and off?

Question

How can I programmatically enable and disable the power to a particular USB port on Linux? Is such a thing even possible? Mac answers appreciated as well!

I was tryi

Answer 1

Don't buy an expensive smart hub just for turning USB gadgets on and off.
All you need is a microcontroller.

Arduino Nano™ ATmega328 *

The Nano is a 16MHz 8-bit computer with 2K RAM and 32K of flash storage.
It has 22 programmable pins (8 analog and 14 digital).
It can read/write USB, and is powered by its 5.0V microUSB port (up to 12.0V external).

// USB Blinker
// Blink LED while receiving USB stream
//
// For Arduino Nano™

int LED = 13;

// setup() is run once at powerup or when reset button is pressed
//
void setup() {
        pinMode(LED, OUTPUT);   // Configure pin D13 as output 
        Serial.begin(9600);     // Open 9600bps USB stream
}

// loop() runs forever at 16Mhz, blinking the LED at 1Hz when receiving USB data.
// 
void loop() { 
        if (Serial.available() > 0) {           // When stream is buffering
                digitalWrite(LED, HIGH);        //   turn on LED 
                delay(500);                     //   wait half second
                digitalWrite(LED, LOW);         //   turn off LED
                delay(500);                     //   wait half second
                while (Serial.available() > 0)  //   drain the buffer
                        Serial.read();         
         }
}

Exquisite tiny cases are available (also free 3d printables).

C4Labs Zebra Black Ice Case


* Use Genuine Arduino Nano™ only. Beware of counterfeits.

UPDATE: Miniaturised ATtiny and wireless microcontollers are also available.