1. Mount the cramfs file system image as a loop device. This will be read-only image.
sudo mount -t cramfs -o loop /tftpboot/img-dnp9200 /media/cramfs/
2. Create a new directory (e.g $HOME/initrd-new) which will be used for modifying the image (RW mode)
3. Go to the mounted cramfs image directory and get the list of files using the following command
- find / > /tmp/filelist.txt
4. Use cpio to copy the contents from the mounted directory to the new directory
- cat /tmp/filelist.txt | cpio -pdm /$HOME/initrd-new
5. modify the contents in the new directory as required.
6. Once the changes are done, use mkcramfs to create the cramfs image again.
- mkcramfs /tmp/new-initrd new-initrd