How to use the command e2image (with examples)

The e2image command is used to save critical ext2/ext3/ext4 filesystem metadata to a file. It allows users to write metadata located on a device to a specific file, print metadata to stdout, restore filesystem metadata back to the device, create a large raw sparse file with metadata at proper offsets, or create a QCOW2 image file instead of a normal or raw image file.

Use case 1: Write metadata located on device to a specific file

Code:

e2image /dev/sdXN path/to/image_file

Motivation: This use case is helpful when users want to save the metadata located on a specific device to a file for backup purposes or further analysis.

Explanation:

• /dev/sdXN: The device to read the metadata from, where X represents the device letter and N represents the partition number.
• path/to/image_file: The path and filename of the file to save the metadata to.

Example output:

Saved ext2 filesystem metadata to 'path/to/image_file'.

Use case 2: Print metadata located on device to stdout

Code:

e2image /dev/sdXN -

Motivation: This use case allows users to view the metadata located on a specific device without saving it to a file.

Explanation:

• /dev/sdXN: The device to read the metadata from, where X represents the device letter and N represents the partition number.
• -: The hyphen represents the stdout output, which will display the metadata on the terminal.

Example output:

Metadata of ext4 filesystem on /dev/sdXN:
...

Use case 3: Restore the filesystem metadata back to the device

Code:

e2image -I /dev/sdXN path/to/image_file

Motivation: This use case is useful when users need to restore the previously saved metadata back to the original device after performing modifications or repairs.

Explanation:

• -I: This flag indicates that the metadata should be restored to the device.
• /dev/sdXN: The device to restore the metadata to, where X represents the device letter and N represents the partition number.
• path/to/image_file: The path and filename of the file containing the saved metadata.

Example output:

Restored ext3 filesystem metadata to /dev/sdXN from 'path/to/image_file'.

Use case 4: Create a large raw sparse file with metadata at proper offsets

Code:

e2image -r /dev/sdXN path/to/image_file

Motivation: This use case is helpful when users need to create a large raw sparse file with metadata, preserving the original filesystem structure and layout.

Explanation:

• -r: This flag enables creating a large raw sparse file.
• /dev/sdXN: The device to read the metadata from, where X represents the device letter and N represents the partition number.
• path/to/image_file: The path and filename of the sparse file to be created.

Example output:

Created raw sparse file 'path/to/image_file' with ext4 filesystem metadata.

Use case 5: Create a QCOW2 image file instead of a normal or raw image file

Code:

e2image -Q /dev/sdXN path/to/image_file

Motivation: This use case is beneficial when users want to create a QCOW2 image file instead of a regular image file, which allows for more flexible storage and snapshot capabilities.

Explanation:

• -Q: This flag specifies the type of image file to create as QCOW2.
• /dev/sdXN: The device to read the metadata from, where X represents the device letter and N represents the partition number.
• path/to/image_file: The path and filename of the QCOW2 image file to be created.

Example output:

Created QCOW2 image file 'path/to/image_file' with ext2 filesystem metadata.

Conclusion:

The e2image command provides users with a range of options to save, print, restore, and create files with ext2/ext3/ext4 filesystem metadata. These use cases allow for efficient backup, analysis, restore, and customization of filesystem metadata. Users can choose the appropriate use case based on their specific requirements.