dumpe2fs command in Linux with examples

dumpe2fs command is used to print the super block and blocks group information for the filesystem present on device.

• Can be used with ext2/ext3/ext4 filesystem for information.
• The printed information may be old or inconsistent when it is used with a mounted filesystem.
• Don't forget to unmount your partition before using this command.

  umount device

Syntax:

dumpe2fs [ -bfhixV ] [ -o superblock=superblock ] [ -o blocksize=block-size ] device

Options:

• b : Used to get the blocks which are reserved as bad in the filesystem.
• o superblock=superblock : It uses the superblock during the examination of filesystem. This option is not usually needed except by a filesystem wizard who is examining the remains of a very badly corrupted filesystem.
• o blocksize=blocksize : It uses the blocksize during the examination of filesystem. This option is not usually needed except by a filesystem wizard who is examining the remains of a very badly corrupted filesystem.
• f : Used to force dumpe2fs to display a filesystem even though it may have some filesystem feature flags which dumpe2fs may not understand.
• h : It will only display the superblock information and not any of the block group descriptor detail information.
• i : Used to show the filesystem data from an image file created by e2image, using device as the pathname to the image file.
• x : Display the detailed group information block numbers in hexadecimal format.
• V : Display the version number of dumpe2fs and exit.

Superblock: It is a record of the characteristics of a filesystem. It includes information about size, block size, empty and the filled blocks. Linux also maintains a copy of its superblock< in memory. If you are unable to mount your device, this can be due to a Corrupted superblock. Examples:

• Displaying superblock information:

  sudo dumpe2fs -h /dev/sda3

  
• Displaying Information of block groups:

  sudo dumpe2fs /dev/sda3

  This displays information about block groups. Notice Primary superblock
• Observing more about superblocks:

  sudo dumpe2fs /dev/sda4 | grep -i superblock

  Displays all available superblocks with discriptors.
• Displaying the version of dumpe2fs:

  sudo dumpe2fs -V