Linux mshowfat Command with Practical Examples

Introduction

In this lab, you will learn about the mshowfat command, a tool used to display information about the FAT (File Allocation Table) file system structure. The mshowfat command is particularly useful for analyzing and troubleshooting issues related to FAT-based storage devices, such as USB drives, memory cards, and older hard disk partitions.

You will start by exploring the basic usage of the mshowfat command, including how to check the installed version and how to display the detailed file system information on a storage device. Additionally, you will learn how to use the mshowfat command to analyze the FAT file system structures, which can be helpful in understanding the organization and layout of the file system.

Linux Commands Cheat Sheet

Skills Graph

Introduction to the mshowfat Command

In this step, you will learn about the mshowfat command, which is a tool used to display information about the FAT (File Allocation Table) file system structure. The mshowfat command is particularly useful for analyzing and troubleshooting issues related to FAT-based storage devices, such as USB drives, memory cards, and older hard disk partitions.

First, let's check the version of mshowfat installed on the system:

mshowfat --version

Example output:

mshowfat version 4.1

The mshowfat command is part of the mtools package, which provides a set of utilities for manipulating FAT-based file systems without mounting the file system. To use mshowfat, you don't need to mount the storage device; instead, you can directly access the file system information.

Let's explore some basic usage of the mshowfat command:

sudo mshowfat /dev/sdb1

This command will display the detailed information about the FAT file system structure on the /dev/sdb1 device. The output will include details such as the file system type, cluster size, number of clusters, and other relevant metadata.

Displaying File System Information with mshowfat

In this step, you will learn how to use the mshowfat command to display detailed information about the FAT file system structure on a storage device.

First, let's create a sample FAT-formatted USB drive. We'll use the mkfs.vfat command to format a loopback device as a FAT file system:

sudo dd if=/dev/zero of=fat_image.img bs=1M count=32
sudo mkfs.vfat fat_image.img

Now, we can use the mshowfat command to display the file system information for the fat_image.img file:

sudo mshowfat fat_image.img

Example output:

FAT file system
Cluster size: 4096 bytes
Number of FATs: 2
Sectors per FAT: 32
Number of clusters: 7936
Root directory entries: 512

The output provides details about the FAT file system, including the cluster size, number of FATs, sectors per FAT, total number of clusters, and the size of the root directory.

You can also use the mshowfat command to display information about a physical storage device, such as a USB drive. Assuming your USB drive is mounted at /dev/sdb1, you can run:

sudo mshowfat /dev/sdb1

This will show the file system information for the USB drive.

Analyzing FAT File System Structures using mshowfat

In this final step, you will learn how to use the mshowfat command to analyze the internal structures of a FAT file system, which can be useful for troubleshooting and understanding the file system layout.

Let's start by creating a sample file and directory structure on the fat_image.img file we created earlier:

sudo mkdir -p fat_image/documents
sudo touch fat_image/documents/sample.txt

Now, let's use the mshowfat command to examine the file system structure in more detail:

sudo mshowfat -v fat_image.img

The -v (verbose) option will provide a more detailed output, including information about the file system's boot sector, FAT tables, and directory entries.

Example output:

FAT file system
Cluster size: 4096 bytes
Number of FATs: 2
Sectors per FAT: 32
Number of clusters: 7936
Root directory entries: 512

Boot sector:
  Jump instruction: EB 58 90
  OEM name: MSWIN4.1
  Bytes per sector: 512
  Sectors per cluster: 8
  Reserved sectors: 1
  Number of FATs: 2
  Root directory entries: 512
  Total sectors: 32768
  Media descriptor: F8
  Sectors per FAT: 32
  Sectors per track: 32
  Number of heads: 64
  Hidden sectors: 0
  Total sectors (long): 32768

FAT 1 at sector 1, FAT 2 at sector 33
Root directory at cluster 2

Directory dump:
  Cluster 2, sector 0, offset 0:
    .          <DIR>        2023-04-12 10:00:00
    ..         <DIR>        2023-04-12 10:00:00
    documents  <DIR>        2023-04-12 10:00:00

  Cluster 3, sector 0, offset 0:
    sample.txt             12 2023-04-12 10:00:00

The detailed output provides information about the file system's boot sector, FAT tables, and the directory structure. You can use this information to understand how the FAT file system is organized and troubleshoot any issues related to file system corruption or data recovery.

Summary

In this lab, you learned about the mshowfat command, a tool used to display information about the FAT (File Allocation Table) file system structure. You explored the basic usage of mshowfat, including checking the installed version and displaying detailed file system information on a storage device. You also learned how to create a sample FAT-formatted USB drive and use mshowfat to analyze its file system structure, such as the cluster size, number of FATs, and the total number of clusters.

Additionally, you gained an understanding of how the mshowfat command can be particularly useful for analyzing and troubleshooting issues related to FAT-based storage devices, without the need to mount the file system.

Linux Commands Cheat Sheet