create live backup on external usb drive

mirror-backup.sh

#!/bin/sh

set -e

if [ "$(id -u)" -ne 0 ]
then
    echo "Rerunning with sudo..."
    fullpath="$(readlink -f $0)"
    exec sudo $fullpath
fi

# the usb drive's filesystem is labelled with 'mirror' so I can grep for it
while true; do
    cat /proc/mounts | grep mirror && break
    echo "waiting for mirror drive mount..."
    sleep 1
done

# mount location of usb/backup drive
ROOT=/media/data/mirror

set +e
rsync_success=0
/usr/bin/rsync -vPaxSHAX --delete --numeric-ids \
    --exclude /home/jae/Private/ \
    / $ROOT
rsync_success="$?"

set -e

# NOTE for disk move
# Mount from rescue disk
# Make filesystem
#mkfs.ext4 /mnt/new
# Sync data
#/usr/bin/rsync -PaxSHAX --delete --numeric-ids /mnt/old/ /mnt/new
# Then do the below, except without the fstab change.

### Make backup bootable
# change to use the mirror disk
sed -i -e 's/LABEL=root/LABEL=mirror/' ${ROOT}/etc/fstab

# required mounts
for fs in dev dev/pts sys proc ; do
	mount -o bind /${fs} ${ROOT}/${fs}
done

# dpkg-reconfigure is only needed if you need to run grub-install
#sudo chroot ${ROOT} dpkg-reconfigure grub-pc
chroot ${ROOT} update-grub
chroot ${ROOT} update-initramfs -t -u -k all

for fs in sys proc dev/pts dev ; do
	umount ${ROOT}/${fs}
done

# done
if [ $rsync_success -gt 0 ]
then
    echo "Rsync failed. Keep mount to re-run? [y/n]"; read reply
    case $reply in Y*|y*) exit 1 ;; *) ;; esac
fi

umount -v $ROOT