OpenBSD Mount And Use a USB Flash Drive

by on May 27, 2007 · 5 comments· LAST UPDATED May 19, 2014

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How do I mount and use a USB pen or hard disk under OpenBSD operating systems using ksh/bash/sh shell prompt?

OpenBSD does supports USB storage devices such as pen and hard disk via emulated SCSI drives. You need to login as root user to mount USB pen/disk.
Tutorial details
DifficultyEasy (rss)
Root privilegesYes
Estimated completion time2m

Finding out your USB device name on an OpenBSD based system

First, insert your your USB flash drive in USB socket. Type the following command to list device names:

# sysctl hw.disknames
Sample outputs:


To get more info about sd0 (my usb pen), type:
# dmesg | grep sd0
Sample outputs:

sd0 at scsibus1 targ 1 lun 0:  SCSI2 0/direct removable
sd0: 1956MB, 512 bytes/sector, 4005888 sectors
sd0 detached
sd0 at scsibus1 targ 1 lun 0:  SCSI2 0/direct removable
sd0: 1956MB, 512 bytes/sector, 4005888 sectors

The following command shows more information about sd0
# disklabel sd0
Sample outputs:

# /dev/rsd0c:
type: vnd
disk: vnd device
label: fictitious
duid: 97d41b01a9d85387
bytes/sector: 512
sectors/track: 100
tracks/cylinder: 1
sectors/cylinder: 100
cylinders: 5120
total sectors: 4005888
boundstart: 0
boundend: 512000
drivedata: 0
16 partitions:
#                size           offset  fstype [fsize bsize  cpg]
  a:           512000                0  4.2BSD   2048 16384    1
  c:          4005888                0  unused

Mounting USB Pen/Hard Disk on an OpenBSD

Type the following command to create a directory (mount point), enter:
# mkdir /mnt/pen

Mount the flash drive using mount command at /mnt/pen, enter:
# mount /dev/sd0i /mnt/pen
You may need to replace /dev/sd0i with actual device name. Now, you can access the files at /mnt/pen:
# cd /mnt/pen
# ls -l
# cp filename /path/to/dir

Finally, unmount the flash filesystem using the following command:
# umount /mnt/pen

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{ 5 comments… read them below or add one }

1 Allan June 30, 2009 at 4:51 pm

“You may need to replace /dev/sd0i with actual device name.”

For people new to OpenBSD, how do you find the actual device name?


2 nixCraft June 30, 2009 at 7:34 pm

Use dmesg. The device shows up in dmesg output after plugging it in. You can also use usbdevs.


3 100 June 7, 2010 at 12:59 am

How did you know the ‘i’ in sd0i? Dmesg only shows ‘sd0′ with no ending.


4 100 August 7, 2010 at 12:44 pm

Answering my own question:

$ disklabel sd0

At the end, you will see the partitions. The i-label denotes a partition.


5 dean October 3, 2010 at 3:37 pm

another way
# sysctl hw.disknames

will show (example)
$ sysctl hw.disknames


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