$ curl cheat.sh/
 cheat.sheets:dumpe2fs 
# Dump information about ext2/3/4 file systems

# Begins with info on Mount path, Inode count etc.
# Then lists the block group information - free inodes etc.
dumpe2fs /dev/sdb1 | less

# Print the blocks which are reserved as bad in the filesystem
dumpe2fs -b /dev/sda2

# Use  the block superblock when examining the filesystem
dumpe2fs -o superblock=superblock /dev/sda1

# Use blocks of blocksize bytes when examining the filesystem.
dumpe2fs -o blocksize=blocksize /dev/sda1

# Force dumpe2fs to display a filesystem
dumpe2fs -f /dev/sda1

# Only display the superblock information
dumpe2fs -h

# Display the filesystem data from an image file created by e2image
dumpe2fs -i

# Print the detailed group information block numbers in hexadecimal format
dumpe2fs -x

 tldr:dumpe2fs 
# dumpe2fs
# Print the super block and blocks group information for ext2/ext3/ext4 filesystems.
# Unmount the partition before running this command using `umount {{device}}`.
# More information: <https://manned.org/dumpe2fs>.

# Display ext2, ext3 and ext4 filesystem information:
dumpe2fs /dev/sdXN

# Display the blocks which are reserved as bad in the filesystem:
dumpe2fs -b /dev/sdXN

# Force display filesystem information even with unrecognizable feature flags:
dumpe2fs -f /dev/sdXN

# Only display the superblock information and not any of the block group descriptor detail information:
dumpe2fs -h /dev/sdXN

# Print the detailed group information block numbers in hexadecimal format:
dumpe2fs -x /dev/sdXN

$
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