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



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