Mounting Filesystems Manually with `mount`

Mastering Manual Mounts: A Guide to Using the `mount` Command in Linux

When it comes to managing file systems in Linux, understanding how to manually mount them is a fundamental skill that every system administrator, and even advanced users, should possess. Mounting a filesystem using the mount command not only allows you to attach file systems to specific directories in the directory tree, but also lets you handle storage devices, ISO images, and network shares more efficiently. In this guide, we'll walk through the basics of using the mount command, including some practical examples and troubleshooting advice.

What is Mounting?

In Linux, mounting refers to the process of making a filesystem accessible by attaching it to a directory. When you mount a filesystem, whether it be from a hard drive, an external storage device, or a network storage, Linux uses that mount point as the root of the filesystem.

Using the `mount` Command

The syntax of the mount command is generally as follows:

mount [options] <device> <directory>

<device>: This is the device file or filesystem source you want to mount.
<directory>: This is the directory where the filesystem will be mounted. This directory is often referred to as the mount point. It must already exist, and it's recommended that it be empty.

Common Usage and Examples

Mounting a USB Drive:

Suppose you have a USB drive identified as /dev/sdb1 and you want to mount it to /mnt/usb. First, ensure that the mount point directory exists:
```
sudo mkdir -p /mnt/usb
```
Next, to mount the USB drive, you would use:
```
sudo mount /dev/sdb1 /mnt/usb
```
After this, accessing /mnt/usb will allow you to access the content of the USB drive.
Mounting an ISO File:

If you want to mount an ISO file to view its contents, you can do so by mounting it to a directory:
```
sudo mkdir /mnt/iso
sudo mount -o loop /path/to/file.iso /mnt/iso
```
Here, -o loop tells mount to treat the file as a loop device.
Viewing All Mounted Filesystems:

You can view a list of all currently mounted filesystems and their properties by just typing:
```
mount
```
Alternatively, for a cleaner output, you might want to use:
```
findmnt
```
Unmounting Filesystems:

To unmount a filesystem, you use the umount command, not "unmount". For our USB example, it would be:
```
sudo umount /mnt/usb
```
Ensure no files are being accessed in the mounted directory when you attempt to unmount.

Options and Flags

-r: Mount the filesystem read-only.
-w: Mount the filesystem read-write (this is the default if not specified).
-t: Specify the type of the filesystem. Common filesystem types include ext4, ntfs, vfat, etc.
```
sudo mount -t ext4 /dev/sdc1 /mnt/data
```
-o: Allows you to specify various mount options like noexec, nosuid, nodev, ro (read-only), etc.

Troubleshooting Tips

Device is busy: This error means that the device or resource is in use. Make sure no processes are using the device or file.
Only root can do that: Mount operations usually require root privileges. Ensure you are using sudo where necessary.
Wrong fs type, bad option, bad superblock: Check if you've specified the correct filesystem type with -t. Also, check the integrity of the filesystem or device.

Understanding the mount command and how file systems work are crucial for effective system administration in Linux. With these skills, you can manage your systems' storage more effectively and troubleshoot related issues with greater confidence.

Mastering Manual Mounts: A Guide to Using the mount Command in Linux