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Modifying the cramfs image

Posted in Linux, Programming by Karthik Murugesan on December 31, 2007

1. Mount the cramfs file system image as a loop device. This will be read-only image.

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
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