Raspbian

2016-05-27-raspbian-jessie.img
2016-05-27-raspbian-jessie-lite.img

`/boot/cmdline.txt`

microSDにイメージを焼いた直後:dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet init=/usr/lib/raspi-config/init_resize.sh
一度でも起動した後: dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait
差分: quiet init=/usr/lib/raspi-config/init_resize.sh

/usr/lib/raspi-config/init_resize.sh

...
main () {

...

if ! parted -m $ROOT_DEV u s resizepart $ROOT_PART_NUM $TARGET_END; then
    FAIL_REASON="Root partition resize failed"
    return 1
  fi

  return 0
}

mount -t proc proc /proc
mount -t sysfs sys /sys

mount /boot
sed -i 's/ quiet init=.*$//' /boot/cmdline.txt
mount /boot -o remount,ro
sync

echo 1 > /proc/sys/kernel/sysrq

...

if main; then
  whiptail --infobox "Resized root filesystem. Rebooting in 5 seconds..." 20 60
  sleep 5
else
...

sedで/boot/cmdline.txtファイルの、quiet から文末まで削除してる
main()で、partedを呼び出している