I need to know how to rebuild the image and i dont understand how to tap up the directory after i delete nova please help

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16# Now we just need to rebuild the image. If you’ve followed my steps above, in ~/pre/resources/webOS/nova run sudo tar cvpzf ../nova-cust-image-castle.rootfs.tar.gz ./
17# In ~/pre/resources/webOS delete nova/ (rm -rf nova). Now tar up this directory run tar cvf ../webOS.tar ./