mshowfat

mshowfat [-b] [-l] [-r] [-s] [-a] [-w] <device>

-b
    Dumps the contents of the boot sector of the filesystem.

-l
    Displays the FAT entries in a linear or detailed, long format.

-r
    Shows information pertaining to the root directory structure within the FAT.

-s
    Provides a short or summary display of FAT entries.

-a
    Displays all available entries in the File Allocation Table.

-w
    (Caution) If supported by this specific `mshowfat` variant, this option would enable write operations, allowing direct modification of the FAT. Use with extreme care as it can lead to data loss.

The `mshowfat` command, part of the `mtools` suite, is a utility designed for in-depth inspection of the File Allocation Table (FAT) on MS-DOS compatible filesystems. It allows users to view the intricate structure of how disk clusters are chained together to form files and directories. This tool is invaluable for low-level filesystem analysis, debugging potential corruption, or simply understanding the underlying disk allocation mechanisms of FAT12, FAT16, or FAT32 volumes. It provides a raw or interpreted view of the FAT, which is crucial for data recovery specialists or developers working with legacy systems.

mshowfat is designed exclusively for MS-DOS FAT filesystems (FAT12, FAT16, FAT32). It typically operates directly on block devices (e.g., /dev/sdb1) or disk image files, often requiring root privileges for direct device access.
While traditionally a read-only diagnostic tool, the presence of a -w option (as indicated in the synopsis) implies potential for direct FAT modification. Such operations carry a significant risk of data loss or filesystem corruption if not performed correctly. Always back up critical data before attempting any write operations.

The command requires a mandatory device argument. This specifies the target FAT filesystem, which can be a physical block device like /dev/fd0 (floppy disk) or /dev/sdb1 (USB drive partition), or a disk image file.

mshowfat is an integral part of the mtools software suite, a collection of utilities developed to enable Linux and Unix-like operating systems to interact with MS-DOS formatted disks and disk images without needing to mount them via the kernel. mtools first emerged in the early days of Linux to facilitate file exchange with DOS-based systems, and its development has paralleled the evolution of FAT filesystems.

mtools(1), mdir(1), mcopy(1), mformat(1)