Linux Disk Mounting¶

📁 Create Mount Point¶

Create a directory to use as a mount point:

mkdir -p /mnt/external_data               # Create mount point directory
mkdir -p /media/usb_drive                 # Alternative for removable media
ls /mnt                                   # List existing mount points
mkdir -p /mnt/wsl/external_data           # Shared mount point across WSL2 distributions

🔌 Mount a Disk¶

Mount a disk with various filesystem options:

sudo mount -t auto /dev/sdg1 /mnt/external_data      # Auto-detect filesystem
sudo mount -t ext4 /dev/sdg1 /mnt/external_data      # Mount ext4 explicitly
sudo mount -t vfat /dev/sdg1 /mnt/external_data      # Mount FAT32
sudo mount -t exfat /dev/sdg1 /mnt/external_data     # Mount exFAT
sudo mount -t xfs /dev/sdg1 /mnt/external_data       # Mount XFS
sudo mount -t ntfs-3g /dev/sdg1 /mnt/external_data   # Mount NTFS (Windows drives)
sudo mount -o ro /dev/sdg1 /mnt/external_data        # Mount read-only
sudo mount -o rw,noexec /dev/sdg1 /mnt/external_data # Mount read-write, no exec

🪟 Mount Windows Drives in WSL2¶

WSL2 allows you to mount standard Windows partitions (like D:) as well as attach bare physical drives.

# Mount a standard Windows partition (e.g., D: drive) using drvfs
sudo mkdir -p /mnt/d
sudo mount -t drvfs D: /mnt/d

# Unmount a drvfs drive
sudo umount /mnt/d

To mount a bare physical disk (e.g., an ext4 Linux drive) into WSL2, run this from an Administrator PowerShell prompt in Windows:

wmic diskdrive list brief                                            # List available physical disks
wsl --mount \\.\PHYSICALDRIVE1 --ext4                                # Mount entire disk as ext4
wsl --mount \\.\PHYSICALDRIVE1 --partition 2 --type ext4             # Mount specific partition
wsl --unmount \\.\PHYSICALDRIVE1                                     # Unmount the physical disk

✅ Verify Mount¶

Confirm the disk is mounted and accessible:

df -h | grep sdg                          # Show disk usage for sdg
df -h /mnt/external_data                  # Show usage for specific mount point
mount | grep sdg                          # Check if disk is mounted
lsblk                                     # List all block devices in tree view
lsblk -f                                  # Include filesystem info
findmnt /mnt/external_data                # Show mount details

🔐 Fix Permissions¶

Adjust ownership and access rights after mounting:

sudo chown -R $USER:$USER /mnt/external_data         # Give current user ownership
sudo chmod -R 755 /mnt/external_data                  # Set standard permissions
sudo chmod -R 777 /mnt/external_data                  # Full access for all users
ls -la /mnt/external_data                             # Verify permissions

🔍 Inspect Disk & Filesystem¶

Identify device names, UUIDs, and filesystem types before mounting:

lsblk                                     # List block devices
lsblk -f                                  # Show filesystem types and UUIDs
sudo fdisk -l                             # List all partitions
sudo blkid                                # Show UUIDs and filesystem types
sudo blkid /dev/sdg1                      # Info for specific partition
sudo file -s /dev/sdg1                    # Detect filesystem type
sudo parted -l                            # Show partition table

🔁 Persistent Mount via `/etc/fstab`¶

Make the mount survive reboots:

# Step 1: Get the UUID of the partition
UUID=$(sudo blkid -s UUID -o value /dev/sdg1)

# Step 2: Append entry to fstab
echo "UUID=$UUID /mnt/external_data ext4 defaults,nofail 0 2" | sudo tee -a /etc/fstab

# Step 3: Test fstab changes without rebooting
sudo mount -a

# Step 4: Verify the mount applied
df -h | grep external_data

Warning

Always use nofail so the system still boots if the drive is unplugged.

fstab Field Reference¶

<device/UUID>  <mountpoint>  <fstype>  <options>  <dump>  <pass>

Field	Common Values	Description
`device`	`UUID=...` or `/dev/sdg1`	Device identifier (UUID preferred)
`mountpoint`	`/mnt/external_data`	Where to mount
`fstype`	`ext4`, `ntfs-3g`, `vfat`, `auto`	Filesystem type
`options`	`defaults`	Standard rw, exec, auto, async flags
`options`	`nofail`	Skip errors on boot if disk missing
`options`	`ro`	Mount read-only
`options`	`noatime`	Don't update access timestamps (faster)
`options`	`uid=1000,gid=1000`	Set owner for FAT/NTFS
`dump`	`0`	`0` = disable backup
`pass`	`0` / `1` / `2`	fsck order: `0`=skip, `1`=root, `2`=others

Filesystem Type Reference¶

Filesystem	Mount Flag	Install Package	Use Case
Auto-detect	`-t auto`	—	Unknown filesystem
ext4	`-t ext4`	built-in	Default Linux filesystem
NTFS	`-t ntfs-3g`	`ntfs-3g`	Windows drives
FAT32	`-t vfat`	built-in	USB drives, SD cards
exFAT	`-t exfat`	`exfat-fuse`	Large USB/SD cards
XFS	`-t xfs`	built-in	High-performance Linux
Btrfs	`-t btrfs`	built-in	Snapshots, modern Linux
ZFS	`-t zfs`	`zfsutils-linux`	Enterprise / NAS
tmpfs	`-t tmpfs`	built-in	RAM-based temp storage
NFS	`-t nfs`	`nfs-common`	Network file shares

Install Required Packages¶

sudo apt install -y ntfs-3g               # NTFS support
sudo apt install -y exfat-fuse exfatprogs # exFAT support
sudo apt install -y nfs-common            # NFS client support
sudo apt install -y zfsutils-linux        # ZFS support

NFS Network Mount¶

Mount a shared folder from another machine on the network:

sudo apt install -y nfs-common                                        # Install NFS client
sudo mount -t nfs 192.168.1.100:/shared /mnt/nfs_share               # Mount NFS share
sudo mount -t nfs -o ro 192.168.1.100:/shared /mnt/nfs_share         # Mount read-only
showmount -e 192.168.1.100                                            # List NFS exports on server

# Persistent NFS fstab entry
echo "192.168.1.100:/shared /mnt/nfs_share nfs defaults,nofail 0 0" | sudo tee -a /etc/fstab

ISO / Image File Mount¶

Mount a disk image or ISO without burning it:

sudo mount -o loop image.iso /mnt/iso                                 # Mount ISO file
sudo mount -o loop,ro disk.img /mnt/image                            # Mount disk image read-only
sudo losetup -f disk.img                                              # Attach image to loop device
sudo losetup -l                                                       # List loop devices
sudo losetup -d /dev/loop0                                            # Detach loop device

Unmount a Disk¶

Safely detach a disk before unplugging:

sudo umount /mnt/external_data            # Unmount by mount point
sudo umount /dev/sdg1                     # Unmount by device name
sudo umount -f /mnt/external_data         # Force unmount (if busy)
sudo umount -l /mnt/external_data         # Lazy unmount (detach when free)
sudo fuser -m /mnt/external_data          # Show processes using the mount
sudo fuser -km /mnt/external_data         # Kill processes and unmount

Filesystem Check & Repair¶

Run fsck to detect and fix filesystem errors (unmount first):

sudo umount /dev/sdg1                     # Must unmount before checking
sudo fsck /dev/sdg1                       # Auto-repair filesystem
sudo fsck -y /dev/sdg1                    # Auto-yes to all repairs
sudo fsck -n /dev/sdg1                    # Dry-run, no changes
sudo e2fsck -f /dev/sdg1                  # Force check on ext2/3/4
sudo ntfsfix /dev/sdg1                    # Fix NTFS errors (basic)

Troubleshooting¶

Symptom	Cause	Fix
`mount: unknown filesystem type`	Missing driver/package	`sudo apt install ntfs-3g` or `exfat-fuse`
`mount: /dev/sdg1 is already mounted`	Previously mounted	`sudo umount /dev/sdg1` first
`mount: wrong fs type or bad superblock`	Corrupt or unknown FS	`sudo file -s /dev/sdg1` to check
`target is busy` when unmounting	Process using mount	`sudo fuser -km /mnt/external_data`
Boot hangs after fstab edit	Bad fstab entry	Add `nofail` option to fstab
`Permission denied` after mount	Ownership not set	`sudo chown -R $USER:$USER /mnt/external_data`
UUID not found	Drive not connected	`lsblk` to confirm device name
`read-only filesystem` error	Dirty NTFS or ext4 error	`sudo fsck -y /dev/sdg1`