Terminal Command to Check Available USB Ports I recently took a trip and was utilizing a USB GPS Device push coordinates to a file.  In the middle of the day the device decided to stop working.  We were never able to get it back working again with my machine.  1 of the possible scenarios (aside from hardware failure on the GPS) we have all but ruled out because of an LED indicator.  This leaves me a bit confused.   My question is 2 fold.  

1) Is it possible for a device on a MAC to not release a USB port? 
2) Is there a way to tell if a USB port is being used at a global system level by any resource?  Can this be done in terminal?
By running

/usr/sbin/system_profiler SPUSBDataType 

I get...

USB:

    USB Bus:

      Host Controller Driver: AppleUSBUHCIPCI
      PCI Device ID: 0x2688
      PCI Revision ID: 0x0009
      PCI Vendor ID: 0x8086

        Generic USB Hub:

          Product ID: 0x0008
          Vendor ID: 0x04fe  (PFU Limited)
          Version: 1.02
          Speed: Up to 12 Mb/sec
          Manufacturer: Chicony
          Location ID: 0x1d100000 / 1
          Current Available (mA): 1000
          Current Required (mA): 64
          Extra Operating Current (mA): 0

            PFU-65 USB Keyboard:

              Product ID: 0x0006
              Vendor ID: 0x04fe  (PFU Limited)
              Version: 1.02
              Speed: Up to 12 Mb/sec
              Manufacturer: Chicony
              Location ID: 0x1d110000 / 2
              Current Available (mA): 1000
              Current Required (mA): 36
              Extra Operating Current (mA): 0

    USB Bus:

      Host Controller Driver: AppleUSBUHCIPCI
      PCI Device ID: 0x268b
      PCI Revision ID: 0x0009
      PCI Vendor ID: 0x8086

    USB Bus:

      Host Controller Driver: AppleUSBUHCIPCI
      PCI Device ID: 0x2689
      PCI Revision ID: 0x0009
      PCI Vendor ID: 0x8086

        USB2.0-Serial:

          Product ID: 0x7523
          Vendor ID: 0x1a86
          Version: 2.54
          Speed: Up to 12 Mb/sec
          Location ID: 0x3d100000 / 1
          Current Available (mA): 1000
          Current Required (mA): 96
          Extra Operating Current (mA): 0

    USB Bus:

      Host Controller Driver: AppleUSBUHCIPCI
      PCI Device ID: 0x268a
      PCI Revision ID: 0x0009
      PCI Vendor ID: 0x8086

        Bluetooth HCI:

          Product ID: 0x8206
          Vendor ID: 0x05ac  (Apple Inc.)
          Version: 19.65
          Speed: Up to 12 Mb/sec
          Location ID: 0x5d200000 / 2
          Current Available (mA): 1000
          Current Required (mA): 0
          Extra Operating Current (mA): 0
          Built-In: Yes

    USB 2.0 Bus:

      Host Controller Driver: AppleUSBEHCIPCI
      PCI Device ID: 0x268c
      PCI Revision ID: 0x0009
      PCI Vendor ID: 0x8086


sed n' grep it to your heart's desire.