==== Create a Swap File ====
<code>
SWAPFILE=/swapfile1
dd if=/dev/zero of=$SWAPFILE bs=1024 count=1048576
mkswap $SWAPFILE
chown root:root $SWAPFILE
chmod 0600 $SWAPFILE
swapon $SWAPFILE
</code>

=== Add to /etc/fstab to make it persistent ===
<code>
echo "$SWAPFILE none swap sw 0 0" >> /etc/fstab
</code>

==== Mount Target System For Chroot ====
<code>
TARGET=/mnt
mount /dev/sdxn $TARGET
mount -t proc proc $TARGET/proc
mount -t sysfs sys $TARGET/sys
mount -o bind /dev $TARGET/dev
mount -t devpts pts $TARGET/dev/pts/
chroot $TARGET
</code>

==== Backup/Restore ====
Refer to `df` or `mount -l`, my excludes:
<code>
/proc/*
/dev/*
/sys/*
/tmp/*
/mnt/*
/media/*
/run/*
/var/lock/*
/var/run/*
/var/log/*.gz
/var/log/**/*.gz
/var/cache/pacman/pkg/*
/home/**/.cache/chromium/*
/home/**/.ccache/*
/home/**/.avfs
/home/**/.gvfs
/lost+found
</code>

Then just `tar cf` as root(-X the excludes rule file).

Restore:

Boot livecd/liveusd, `cfdisk` and `mkfs`, then mount it(see instructions above) to /target. Then:
<code>
tar xf /path/to/your/backup.tar -C /target
</code>

or get backup and extract in pipe:
<code>
ssh user@host cat /path/to/your/backup.tar |tar x -C /target
</code>

Rsync:
<code>
# rsync -aAXvzP --delete / /target/ --exclude-from=/path/to/backup.excludes
</code>

Get UUID using `blkid` and change `/etc/fstab` of target accordingly.

If newly-installed, `chroot` into it, run `grub-install` and `update-grub`, give it a `reboot` and it would work!
Else, just update UUIDs in /boot/grub/menu.lst for grub-legacy.

==== update-grub For Grub2 ====
For those who doesn't have this:
<code>
grub-mkconfig -o /boot/grub/grub.cfg
</code>

==== Don't Stop at Grub Screen FOREVER (WTF Ubuntu) ====
<code>
echo "GRUB_RECORDFAIL_TIMEOUT=5" >> /etc/default/grub
</code>

==== Specify I/O Scheduler For Drive Specified By Partition UUID ====
<code>
echo "noop" > /sys/block/`readlink /dev/disk/by-uuid/$UUID|sed "s/.*\(sd[a-z]\).*/\1/"`/queue/scheduler
</code>

==== Install Artful Kernel (4.13) on Xenial ====
<code>
echo 'deb http://archive.ubuntu.com/ubuntu/ artful main' >> /etc/apt/sources.list.d/artful.list
echo -e 'Package: *\nPin: release a=artful\nPin-Priority: 100\n' >> /etc/apt/preferences.d/artful.pref
apt-get update
apt-get install -t artful linux-image-generic linux-generic linux-headers-generic linux-libc-dev
</code>

References:

  * http://apt-blog.net/backup_or_migrate_linux_system_using_tar
  * http://www.cyberciti.biz/faq/linux-add-a-swap-file-howto/
  * https://axebase.net/blog/2016/12/27/zesty-kernel-in-yakkety-und-xenial/