dumpe2fs
Display ext2/3/4 filesystem information
TLDR
Display ext2, ext3, and ext4 filesystem information
Display the blocks which are reserved as bad in the filesystem
Force display filesystem information even with unrecognizable feature flags
Only display the superblock information and not any of the block group descriptor detail information
Print the detailed group information block numbers in hexadecimal format
SYNOPSIS
dumpe2fs [options] <device>
PARAMETERS
-b blocksize
Specify filesystem blocksize instead of detecting from superblock.
-e
List external journal device if present.
-g blockgroup
Show information for specific block group only.
-h
Print superblock information only (no block groups).
-i inode
Dump contents of specified inode.
-j
Print journal usage information.
-k
Cause dumpe2fs to print the bad block list.
-m
Display superblock and block group descriptors in hex.
-o superblock
Use superblock at specified block location.
-x bad-block
Dump specified bad block.
-V
Print version information and exit.
DESCRIPTION
dumpe2fs is a command-line utility from the e2fsprogs package used to display detailed information about the superblock and block group descriptors of ext2, ext3, and ext4 filesystems. It is invaluable for system administrators and developers debugging filesystem issues, recovering data, or verifying filesystem integrity.
The tool reads directly from the block device, extracting parameters like block and fragment sizes, total blocks and inodes, filesystem state (clean/mounted), feature flags, journal details, reserved blocks, and mount counts. Block group information reveals inode table locations, block bitmaps, and usage statistics across groups.
Primarily read-only, it poses no risk to mounted filesystems but requires appropriate permissions. Output helps diagnose problems like backup superblock locations for fsck recovery or journal UUIDs for external journals. Custom options allow focusing on specific inodes, bad blocks, or alternate superblocks, making it a key tool alongside debugfs and tune2fs.
Usage is straightforward on Linux systems with ext*-formatted devices/partitions.
CAVEATS
Requires read access to block device (often root). Safe on mounted filesystems as read-only, but avoid on active writes for accuracy.
EXAMPLE
dumpe2fs -h /dev/sda1
Dumps superblock info only for quick overview.
dumpe2fs -m /dev/sda1
Hexdump of superblock and groups.
HISTORY
Part of e2fsprogs suite, developed by Remy Card, Theodore Ts'o, and others starting in 1993 for ext2. Extended for ext3 (2001) journaling and ext4 (2008) features.
