Mount drives on OpenBSD

Only root can mount(8) file systems on OpenBSD, a regular user should use doas(1).

Plug in your USB drive and check system messages:

# dmesg
sd1 at scsibus2 targ 1 lun 0: <Vendor, Model, 1.26>
SCSI3 0/direct removable serial.12345678901234568789
sd1: 7633MB, 512 bytes/sector, 15633408 sectors

Check partitions:

# disklabel sd1
          size     offset  fstype [fsize bsize   cpg]
  a:    736256       1024  4.2BSD   2048 16384 16142
  c:  15633408          0  unused
  i:       960         64   MSDOS

Let’s say you want to mount the first partition (a:), then the device you’re looking for is /dev/sd1a. Create the mount point directory, say /mnt/usb-drive, and mount the drive:

# mkdir -p /mnt/usb-drive
# mount /dev/sd1a /mnt/usb-drive
# ls /mnt/usb-drive

Hooray! Now it’s mounted.

Before disconnecting the drive from the USB port, make sure it’s unmounted, to that you’ll need to leave mount point directory and then use it as an argument for unmount(8).

# cd
# umount /mnt/usb-drive

Or you can address your device directly:

# cd
# umount /dev/sd1a

That’s it.

If you’d like to automate these steps, check mnt() and umnt() functions from my ~/.profile.