35 lines
904 B
Bash
35 lines
904 B
Bash
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#!/bin/bash
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# Copies raspi3.img into compr.img, resulting in many consecutive zero bytes
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# which are nicely compressible.
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set -e
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qemu-img create -f raw compr.img 1000M
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# copy partition table from raspi3.img
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sfdisk --quiet --dump raspi3.img | sfdisk --quiet compr.img
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readarray rmappings < <(sudo kpartx -asv raspi3.img)
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readarray cmappings < <(sudo kpartx -asv compr.img)
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# copy the vfat boot partition as-is
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set -- ${rmappings[0]}
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rboot="$3"
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set -- ${cmappings[0]}
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cboot="$3"
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sudo dd if=/dev/mapper/${rboot?} of=/dev/mapper/${cboot?} bs=5M status=none
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# copy the ext4 root partition in a space-saving way
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set -- ${rmappings[1]}
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rroot="$3"
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set -- ${cmappings[1]}
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croot="$3"
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sudo e2fsck -y -f /dev/mapper/${rroot?}
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sudo resize2fs /dev/mapper/${rroot?} 700M
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sudo e2image -rap /dev/mapper/${rroot?} /dev/mapper/${croot?}
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sudo kpartx -ds raspi3.img
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sudo kpartx -ds compr.img
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bzip2 -k -9 -f compr.img
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