/usr/bin/abootimg-unpack-initrd is in abootimg 0.6-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | #!/bin/sh
#
initrd=${1:-initrd.img}
ramdisk=${2:-ramdisk}
if [ ! -f $initrd ]; then
echo "$initrd does not exist."
exit 1
fi
if [ -d $ramdisk ]; then
echo "$ramdisk already exists."
exit 1
fi
mkdir -p $ramdisk
zcat $initrd | ( cd $ramdisk; cpio -i )
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