mount Command Linux: Complete Guide to Mount Filesystems and Drives

The mount command is one of the most fundamental tools in Linux system administration, allowing you to attach filesystems from various storage devices to your directory tree. Whether you’re working with hard drives, USB devices, network shares, or virtual filesystems, understanding the mount command is essential for effective Linux system management.

What is the mount Command?

The mount command in Linux is used to attach a filesystem from a storage device to a specific directory (called a mount point) in your system’s directory tree. This process makes the files and directories on the storage device accessible through the Linux filesystem hierarchy.

When you mount a filesystem, you’re essentially telling the operating system where to find the data on a particular device and where users should access it within the directory structure.

Basic Syntax and Usage

The basic syntax of the mount command follows this pattern:

mount [options] device mountpoint
mount [options] device
mount [options] mountpoint

Simple Mount Example

Let’s start with a basic example of mounting a USB drive:

sudo mount /dev/sdb1 /mnt/usb

This command mounts the first partition of the second SCSI/SATA/USB device (/dev/sdb1) to the directory /mnt/usb.

Viewing Currently Mounted Filesystems

To see all currently mounted filesystems, simply run the mount command without any arguments:

mount

Sample output:

/dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro)
/dev/sda2 on /home type ext4 (rw,relatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noexec)
/dev/sdb1 on /mnt/usb type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)

For a more readable format, you can use:

mount | column -t

Common Mount Options

Mount options control how the filesystem behaves after mounting. Here are the most commonly used options:

Access Control Options

• rw: Mount read-write (default)
• ro: Mount read-only
• exec: Allow execution of binaries (default)
• noexec: Prevent execution of binaries
• suid: Allow set-user-ID and set-group-ID bits (default)
• nosuid: Ignore set-user-ID and set-group-ID bits

Example with Options

sudo mount -o ro,noexec,nosuid /dev/sdb1 /mnt/secure-usb

This mounts the USB drive with enhanced security: read-only, no execution of binaries, and ignoring SUID bits.

Filesystem Types

Linux supports numerous filesystem types. You can specify the filesystem type using the -t option:

sudo mount -t ext4 /dev/sdb1 /mnt/data
sudo mount -t ntfs /dev/sdc1 /mnt/windows
sudo mount -t vfat /dev/sdd1 /mnt/fat32

Common Filesystem Types

• ext4: Default Linux filesystem
• ext3/ext2: Older Linux filesystems
• ntfs: Windows NTFS filesystem
• vfat: FAT32 filesystem
• xfs: High-performance filesystem
• btrfs: Modern copy-on-write filesystem

Mounting Different Types of Storage

Mounting USB Drives

First, identify your USB device:

lsblk

Sample output:

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 465.8G  0 disk 
├─sda1   8:1    0   512M  0 part /boot/efi
├─sda2   8:2    0     1G  0 part /boot
└─sda3   8:3    0 464.3G  0 part /
sdb      8:16   1  14.9G  0 disk 
└─sdb1   8:17   1  14.9G  0 part

Mount the USB drive:

sudo mkdir -p /mnt/usb
sudo mount /dev/sdb1 /mnt/usb

Mounting ISO Files

You can mount ISO files as loop devices:

sudo mount -o loop /path/to/image.iso /mnt/iso

For read-only mounting:

sudo mount -o loop,ro /path/to/image.iso /mnt/iso

Mounting Network Shares

NFS Shares

sudo mount -t nfs 192.168.1.100:/shared/folder /mnt/nfs

SMB/CIFS Shares

sudo mount -t cifs //192.168.1.100/shared /mnt/smb -o username=user,password=pass

For security, use a credentials file:

sudo mount -t cifs //192.168.1.100/shared /mnt/smb -o credentials=/etc/cifs-credentials

Advanced Mount Techniques

Bind Mounts

Bind mounts allow you to mount a directory to another location:

sudo mount --bind /original/path /new/path

Example:

sudo mount --bind /home/user/documents /mnt/docs

Temporary Filesystems (tmpfs)

Create a RAM-based filesystem:

sudo mount -t tmpfs -o size=1G tmpfs /mnt/ramdisk

Mounting with Specific User Permissions

For NTFS and FAT filesystems, you can specify user and group ownership:

sudo mount -t ntfs /dev/sdb1 /mnt/windows -o uid=1000,gid=1000,umask=022

Using /etc/fstab for Permanent Mounts

The /etc/fstab file contains information about filesystems that should be mounted automatically at boot time.

fstab Format

Each line in /etc/fstab contains six fields:

device mountpoint filesystem options dump pass

Example fstab Entries

# Static filesystem table
UUID=12345678-1234-1234-1234-123456789012 / ext4 defaults 0 1
UUID=87654321-4321-4321-4321-210987654321 /home ext4 defaults 0 2
/dev/sdb1 /mnt/backup ext4 defaults,noauto 0 0
tmpfs /tmp tmpfs defaults,size=2G 0 0

Testing fstab Entries

Before rebooting, test your fstab entries:

sudo mount -a

Unmounting Filesystems

To unmount a filesystem, use the umount command:

sudo umount /mnt/usb

You can unmount by device or mount point:

sudo umount /dev/sdb1
sudo umount /mnt/usb

Forcing Unmount

If a filesystem is busy, you can force unmount (use with caution):

sudo umount -f /mnt/usb

For network filesystems, use lazy unmount:

sudo umount -l /mnt/nfs

Troubleshooting Common Issues

Device or Resource Busy

When you can’t unmount because the filesystem is busy:

# Find processes using the mount point
sudo lsof /mnt/usb
# Or use fuser
sudo fuser -v /mnt/usb

Finding Block Device Information

Use these commands to identify devices:

# List all block devices
lsblk

# Show device UUIDs
sudo blkid

# Show partition information
sudo fdisk -l

Permission Issues

For permission problems with mounted filesystems:

# Mount with specific permissions
sudo mount -o uid=1000,gid=1000,umask=002 /dev/sdb1 /mnt/usb

# Change ownership after mounting (for some filesystems)
sudo chown user:group /mnt/usb

Security Considerations

Secure Mount Options

For removable media, consider these security options:

sudo mount -o ro,noexec,nosuid,nodev /dev/sdb1 /mnt/secure

User Mounts

Allow users to mount specific devices by adding the user option in /etc/fstab:

/dev/sdb1 /mnt/usb vfat user,noauto,rw 0 0

Then users can mount with:

mount /mnt/usb

Performance Optimization

Mount Options for Performance

For better performance, consider these options:

# For SSD drives
sudo mount -o defaults,noatime,discard /dev/sdb1 /mnt/ssd

# For network filesystems
sudo mount -t nfs -o rsize=8192,wsize=8192,timeo=14 server:/path /mnt/nfs

Monitoring and Maintenance

Checking Mount Status

Monitor mount points and usage:

# Show disk usage for mounted filesystems
df -h

# Show mount points in tree format
findmnt

# Monitor filesystem activity
sudo iotop

Best Practices

1. Always create mount points before mounting:

   sudo mkdir -p /mnt/device-name

2. Use UUIDs in fstab for reliability:

   UUID=12345678-1234-1234-1234-123456789012 /home ext4 defaults 0 2

3. Test fstab changes before rebooting:

   sudo mount -a

4. Use appropriate security options for different use cases
5. Keep mount points organized under /mnt or /media
6. Always unmount properly before removing devices

Conclusion

The mount command is a powerful and essential tool for Linux system administration. From basic filesystem mounting to complex network shares and security configurations, mastering the mount command enables you to effectively manage storage resources in your Linux environment.

Whether you’re mounting USB drives for data transfer, setting up network shares for collaboration, or configuring automatic mounts for system boot, the mount command provides the flexibility and control needed for modern Linux systems. Remember to always follow security best practices and test your configurations thoroughly before implementing them in production environments.

With the knowledge and examples provided in this guide, you’re well-equipped to handle various mounting scenarios and troubleshoot common issues that may arise in your Linux journey.