How to Open USB Connected Devices on a Mac (With Terminal Steps)

Eric DawsonByEric Dawson Computers & Software

To learn how to open USB connected devices on Mac, open Finder and select the drive under Locations to browse its files. USB hard drives, SSDs, and SD cards may also appear on the Desktop. If the drive is not in Finder, open Applications > Utilities > Disk Utility, select the device or volume, and click Mount.

For every USB device macOS recognizes, hold Option, click the Apple menu, choose System Information or System Profiler, then select USB. The USB Device Tree shows devices beneath their ports, including hubs and some internal hardware. In Terminal, run ioreg -p IOUSB to list USB hardware, or use open /Volumes/volume_name to open an already mounted drive.

Open USB Connected Devices on a Mac

Start with Finder when you want to open files on a USB drive, SSD, hard drive, or SD card. Storage devices appear under Locations in a Finder window, where selecting the drive opens its contents. Hardware such as keyboards, cameras, audio interfaces, hubs, and adapters does not open like a folder, but macOS can still identify it as a connected USB device.

Open a USB Storage Device

Finder is the usual place to browse a mounted USB drive. If the drive is connected but does not appear in the Finder sidebar, Disk Utility can show connected disks under External and can mount a visible volume. Desktop visibility is separate from Finder sidebar visibility, so a drive can be available in Finder without appearing on the Desktop.

  1. Click the Finder icon in the Dock to open a Finder window.
  2. Look under Locations for the connected external drive.
  3. Select the drive name to view its folders and files.
  4. Open Applications > Utilities > Disk Utility if the drive is not shown in Finder.
  5. Return to Finder and select the mounted drive under Locations.

Hardware detection serves a different purpose from opening storage. System Information USB shows every USB device the Mac recognizes, including hubs and some internal hardware, while Finder is for mounted storage you can browse. Terminal can also list USB hardware with ioreg -p IOUSB, making it useful when you need to view USB devices in Terminal rather than open files.

Apple-silicon Mac laptops may ask you to approve a new or unknown USB, Thunderbolt, or SD accessory before macOS allows it to connect. Unlock the Mac first if it is locked, then allow the accessory when prompted. Choosing “Don’t Allow” prevents the Mac from recognizing the accessory or giving it access to data, although the accessory may still receive power or charge the Mac.

Accessory approval settings are available through Apple menu > System Settings > Privacy & Security > Accessories. For a mounted storage drive, Terminal can open its Finder location with open /Volumes/volume_name, replacing volume_name with the drive’s name.

Find USB Storage in Finder and Disk Utility

If the device is connected but you do not see it in the sidebar, open Finder by clicking the blue smiley-face icon in the Dock. From the Finder menu, choose Finder > Settings, then review the Sidebar options under Locations and enable the relevant external-device options.

Choose Finder > Settings or Preferences > General to control which items Finder shows there. When a drive is visible in the sidebar but absent from the Desktop, select the appropriate external-disk option under “Show these items on the Desktop.” A USB-A or USB-C connection follows the same Finder display process.

Once a storage device is connected but does not appear in Finder, check Disk Utility. For that route, open Applications > Utilities, then launch Disk Utility. Disk Utility lists connected disks in its External section, including devices that are not currently mounted. Select the visible drive or its volume in the sidebar, then click Mount to make the storage available in Finder.

Use Finder after the volume mounts to browse the drive’s contents. After mounting, the drive should appear under Locations if the Finder sidebar is set to show external disks. Then select its name to open it like any other folder on the Mac.

Used bookstores suit me because a spine on a shelf is not the same thing as a book I can actually take home, a distinction I manage to overapply with great seriousness. In Finder and Disk Utility, USB storage follows the same rule: a drive listed under External still needs its volume mounted before Finder can open its contents.

List USB Devices on a Mac in System Information

Alternatively, open Apple menu > About This Mac > More Info > System Report, then choose USB under Hardware in the sidebar.

Apple notes that the tree can include an internal FaceTime HD camera, a keyboard hub, or a display hub, so an entry is not necessarily an external accessory. Devices may appear beneath several levels when they are connected through a dock, display, keyboard, or other hub.

Read the USB Device Tree

Select an item in the device tree to find USB device information and inspect its speed designation in the lower part of the window. Some listings can include capacity, file system, volume UUID, free space, current required, and writeability.

Because Macs and displays can group built-in ports as hubs, the tree is not always a one-port-per-bus map. Apple gives Mac Pro front and rear port groups as an example. Each bus can therefore represent a connection path rather than one physical socket alone.

Use the following routes to list USB devices on a Mac and interpret the System Information view.

Task Mac Method What You See
See recognized USB hardware Hold Option, click Apple menu, choose System Information, then USB A USB Device Tree with connected hardware and hubs
Use the System Report route Apple menu > About This Mac > More Info > System Report > USB USB buses with attached devices beneath them
Check connection speed Select a device in the tree A speed designation in the lower part of the window
Check a missing device Look under another USB bus Whether the Mac recognizes the hardware through a different connection path

A fast USB device can communicate more slowly when connected through a slower port or hub. Apple lists USB 3 at 5 Gbp/sec, USB 2 at 480 Mbp/sec, and USB 1 at 1.5 Mbp/sec.

Connecting a USB 2 keyboard to a USB 3 port, however, does not raise the keyboard’s operating speed. Before using a hub, check its speed, particularly on older hardware. For an iOS device, use a port or hub listed as 480 Mb/sec or faster.

When expected hardware is missing from a USB bus, try another bus. If it remains absent from System Report, restart the Mac, then try another cable, port, or a direct connection rather than a hub. Comparing the USB Device Tree before and after reconnecting hardware can help isolate a cable, device, hub, or port issue. System Information identifies hardware that macOS sees, while the device tree can also include internal components that are not meant to be opened as external devices.

View USB Devices in Terminal

For this Terminal method, start with ioreg -p IOUSB to view the Mac’s USB device registry.

Open Terminal from Applications > Utilities, enter the command, and press Return.

For a shorter plain-text list of attached device names, run ioreg -p IOUSB -w0 | sed ‘s/[^o]*o //; s/@.*$//’ | grep -v ‘^Root.*’. Here, -p IOUSB limits the output to USB devices, while -w0 prevents long entries from being truncated. The sed and grep portions reduce the results to device names and remove the initial root-summary line.

Alternatively, use system_profiler SPUSBDataType for macOS’s built-in USB hardware report in Terminal. That command can be useful when you want more complete USB device information than a shortened device-name list provides. Comparing its output before and after you connect an accessory can help show which entry belongs to that accessory.

Keep in mind that Terminal does not limit results to external devices. A Mac laptop’s built-in keyboard or trackpad can appear in a USB listing, along with internal hardware and hubs built into displays or keyboards. Consequently, an unfamiliar item in the output is not automatically a USB device plugged into the Mac.

Mounted external drives can be listed separately with diskutil list external. For an already mounted volume, use the open command. Use that command only for a volume that is already mounted.

Mount a USB Drive with Terminal

Terminal can mount a USB disk with the diskutil command, then open a volume after macOS has mounted it. The opening command applies to a mounted volume, so mounting comes first when the drive is not yet available.

Mount the Disk

To mount a USB disk, run diskutil mountDisk /dev/diskX in Terminal. Replace diskX with the disk identifier for the USB disk you want to mount. That command mounts the disk so its storage volume can become available to Finder and other Mac apps.

Substitute the name shown for that volume in place of volume_name. Opening the volume this way launches it through macOS, much like selecting a mounted drive to browse its contents.

Work with the Mounted Volume Path

Ask Different community members report that mounted drives commonly have folders in /Volumes that match the names shown in Finder or on the Desktop. Their reported methods include using ls /Volumes to look for a newly connected drive and df -h to view a mount point such as /Volumes/NO NAME. Posters in those community discussions also say that mount can show mounted volumes and their mount points.

Remember that diskutil list external lists external USB drives that are already mounted on the Mac. A drive that has not mounted may therefore need the diskutil mountDisk /dev/diskX command before it can be opened with open. Comparing Terminal output before and after connecting a device can help narrow down which entry changed when you are working with more than one connected drive.

Check Ports, Hubs, and Connection Speed

System Information can show a connected device’s speed designation, helping you spot when a port or hub may limit communication. Select the device in the USB Device Tree and check the lower part of the window for its listed speed. A fast device connected through a slower port can communicate with the Mac at a slower rate.

Compare the Device, Port, and Hub

Hubs deserve the same attention as the Mac port because they can create a bottleneck between the device and computer. Even a fast external SSD cannot avoid a slower connection in the path through a port or hub. For the best result, connect the fastest USB devices to the fastest available Mac ports. Conversely, attaching a slower device to a faster port does not increase that device’s own speed, just as a USB 2 keyboard still operates at USB 2 speeds when plugged into a USB 3 port.

Port groups in Mac System Information USB may appear as hubs rather than as a simple one-port-per-bus list. That layout helps explain why a device may appear beneath a hub entry instead of directly beneath a port. Before relying on a hub for a high-speed device, check its speed, since not every hub uses USB 2 or a newer standard, particularly on older hardware.

Use the Speed Reading to Test Connections

When a device seems slower than expected, compare its speed designation with the port and hub it uses. Try moving the device to another USB bus or connecting it directly to the Mac instead of through a hub or dock. Restart the Mac and test another cable if the device does not appear through the usual USB device information views. Persistent connection problems can involve the cable, jack, device, hub, or a Mac USB port.

Troubleshoot a USB Device Your Mac Cannot See

First, restart the Mac if a USB device is missing from Finder, System Report, and Terminal. On reconnecting the device, try a different cable, another port, and a direct connection instead of a hub or dock.

Approve Accessories on Apple-Silicon Mac Laptops

When that alert appears, unlock the Mac and choose to allow the accessory so macOS can recognize it and give it access to data.

To change this behavior, open Apple menu > System Settings > Privacy & Security, scroll to Accessories, then use the menu beside “Allow accessories to connect.” Available choices include “Always ask,” “Ask for new accessories,” and “Automatically allow when unlocked.”

After a Mac laptop has been locked for 3 or more days, an accessory that was previously approved may require the Mac to be unlocked again. Next, if you use the laptop with its lid closed, allow the external display, mouse, and keyboard before closing the lid or using a docking station. Then other accessories can be approved without opening the lid. Compare the list USB devices Mac output before and after connecting the device when you need to see whether macOS detects a change at all.

Check the Connection and the Device

For a storage device that remains absent, unplug it and reconnect it, test another enclosure if one is in use, and try the device on another computer. Unreadable drives can also have a physical lock, require decryption on Windows if BitLocker-encrypted, or need a Mac-compatible file system.

BitLocker-encrypted media may need to be decrypted on Windows before its contents can be read on the Mac. Reformatting in Disk Utility is an option when a storage device is formatted incorrectly, but wiping a drive removes its existing contents. Comparing connection results can help narrow the issue to an external power requirement, cable, jack, device, or a USB port on the Mac or hub.

Frequently Asked Questions

Why Does My USB Device Show in System Information but Not Finder?

System Information identifies USB hardware that macOS recognizes, including internal hardware and hubs, while Finder is for mounted storage volumes. If the device is a storage drive, open Disk Utility from Applications > Utilities, select the device or volume under External, and click Mount. Once mounted, it should be available in Finder under Locations.

How Do I List USB Devices in Terminal on a Mac?

Open Terminal from Applications > Utilities and run ioreg -p IOUSB to list USB hardware connected to the Mac. You can also run system_profiler SPUSBDataType, which uses macOS’s built-in system profiler. Either command can include internal USB hardware, such as a built-in keyboard, trackpad, camera, or internal hub.

How Do I Mount a USB Drive from Terminal?

Use diskutil mountDisk /dev/diskX, replacing diskX with the drive’s disk identifier, to mount a USB disk from Terminal. After mounting, open it in Finder. Disk Utility also lets you select a visible volume and click Mount.

Why Does a USB Device Appear as a Hub in System Information?

System Information’s USB Device Tree can show hubs as well as individual accessories. Some hubs are built into keyboards and displays, and some Macs or displays group built-in ports under a hub. Apple gives the example of a Mac Pro that can show its front ports as one hub and its rear ports as another.

What Should I Do if My Apple-Silicon Mac Asks to Allow a USB Accessory?

Unlock the Mac, then approve the new or unknown USB, Thunderbolt, or SD accessory when macOS displays the alert. Choosing “Don’t Allow” prevents the Mac from recognizing the accessory or giving it access to data, although the accessory may still charge. Accessory behavior can be changed in Apple menu > System Settings > Privacy & Security > Accessories.

Finder is the place to browse files on a mounted USB storage drive, while System Information and Terminal help confirm that macOS recognizes connected hardware. Disk Utility can mount a visible storage volume, and System Information can help identify ports, hubs, and connection speeds. When a device is absent, try another USB bus, restart the Mac, test another cable or port, and bypass a hub. Apple-silicon Mac laptops may also require accessory approval after unlocking.

References

Sources read in September 2026.

Eric Dawson

I'm Eric Dawson, and I write The Money Watch from north Columbus, Ohio. Most of what I cover comes from my own life: renting, a 2014 Honda Fit, parking, computers, food and the bills behind all of it. I spent four years in an apartment-property office and eleven on a distributor's operations desk, reading leases and invoices. Where you need real information, I research the maker's or agency's own page and independent sources and report what they publish. I don't give tax, investment, legal or medical advice.