Mac OS X

All recent releases of macOS (formerly OSX) should detect and contain drivers for genuine Arduino, and most reputable clones.

The first step is to see if the USB device is recognised.

Running System Information and inspecting Hardware/USB will show devices. This is also available from  About this Mac/System Report

An Arduino Uno will show an entry like:-

Communication Device: Product ID: 0x0043 Vendor ID: 0x2341 Version: 0.01 Serial Number: 5543434373335120A2B0 Speed: Up to 12 Mb/sec Manufacturer: Arduino (www.arduino.cc) Location ID: 0xfa130000 / 5 Current Available (mA): 500 Current Required (mA): 100 Extra Operating Current (mA): 0 

NOTE The listing will not be updated if devices are inserted, and needs to be run AFTER the Arduino is plugged in.

Alternatively, running ioreg -b -p IOUSB will show a compact list of devices in Terminal, but it is difficult to interpret. The same Uno generates a line such as:-

IOUSBHostDevice@fa130000 <class AppleUSBDevice, id 0x1000014b0, registered, matched, active, busy 0 (5663 ms), retain 16> 

This method is more suited to a before/after approach to see if a new device appears, after it has been plugged in.