150 lines
4.9 KiB
Bash
Executable File
150 lines
4.9 KiB
Bash
Executable File
#!/usr/bin/env bash
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# adafruit-pi-externalroot-helper
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#
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# Configure a Raspbian system to use an external USB drive as root filesystem.
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#
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# See README.md for details and sources.
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set -e
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function print_version() {
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echo "Adafruit Pi External Root Helper v0.1.0"
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exit 1
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}
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function print_help() {
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echo "Usage: $0 -d [target device]"
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echo " -h Print this help"
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echo " -v Print version information"
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echo " -d [device] Specify path of device to convert to root"
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echo
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echo "You must specify a device. See:"
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echo "https://learn.adafruit.com/external-drive-as-raspberry-pi-root"
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exit 1
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}
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# Display an error message and quit:
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function bail() {
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FG="1;31m"
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BG="40m"
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echo -en "[\033[${FG}\033[${BG}error\033[0m] "
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echo "$*"
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exit 1
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}
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# Display an info message:
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function info() {
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task="$1"
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shift
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FG="1;32m"
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BG="40m"
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echo -e "[\033[${FG}\033[${BG}${task}\033[0m] $*"
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}
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if [[ $EUID -ne 0 ]]; then
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bail "must be run as root. try: sudo adafruit-pi-externalroot-helper"
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fi
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# Handle arguments:
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args=$(getopt -uo 'hvd:' -- $*)
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[ $? != 0 ] && print_help
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set -- $args
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for i
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do
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case "$i"
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in
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-h)
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print_help
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;;
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-v)
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print_version
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;;
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-d)
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target_drive="$2"
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echo "Target drive = ${2}"
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shift
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shift
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;;
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esac
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done
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if [[ ! -e "$target_drive" ]]; then
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bail "Target ${target_drive} must be existing device (use -d /dev/foo to specify)"
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fi
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info "start" "Will create new ext4 filesystem on ${target_drive}"
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info "start" "If there is data on ${target_drive}, it will be lost."
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read -p "Really proceed? (y)es / (n)o " -n 1 -r
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echo
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if [[ ! $REPLY =~ ^[Yy]$ ]]
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then
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echo "Quitting."
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exit
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fi
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export target_partition="${target_drive}1"
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info "dependencies" "Installing gdisk, rsync, and parted."
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# All except gdisk are probably installed, but let's make sure.
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apt-get install gdisk rsync parted
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info "fs create" "Creating ${target_partition}"
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# The alternative here seems to be to pipe a series of commands
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# to fdisk(1), similar to how it's done by raspi-config:
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# https://github.com/asb/raspi-config/blob/3a5d75340a1f9fe5d7eebfb28fee0e24033f4fd3/raspi-config#L68
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# This seemed to work, but I was running into weirdness because
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# that doesn't seem to make a GPT, and later on I couldn't get
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# partition unique GUID from gdisk. parted(1) is also a nice
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# option because it's scriptable and allows partition sizes to
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# be specified in percentages.
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parted --script "${target_drive}" mklabel gpt
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parted --script --align optimal "${target_drive}" mkpart primary ext4 0% 100%
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info "fs create" "Creating ext4 filesystem on ${target_partition}"
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mkfs -t ext4 -L rootfs "${target_partition}"
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info "fs id" "Getting UUID for target partition"
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eval `blkid -o export "${target_partition}"`
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export target_partition_uuid=$UUID
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info "fs id" "Getting Partition unique GUID for target filesystem"
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# Ok, so the only way I was able to get this was using gdisk.
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# I don't quite understand the different between this value and
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# the one you can get with blkid and tune2fs (which seem to give
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# the same thing). Nevertheless, this seems to be necessary to
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# get a value that can be used in cmdline.txt. I think it's a
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# GUID specifically for the GPT partition table entry.
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export partition_unique_guid=`echo 'i' | sudo gdisk "${target_drive}" | grep 'Partition unique GUID:' | awk '{print $4}'`
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info "fs id" "Target partition UUID: ${target_partition_uuid}"
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info "fs id" "Partition unique GUID: ${partition_unique_guid}"
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info "fs copy" "Mounting ${target_partition} on /mnt"
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mount "${target_partition}" /mnt
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info "fs copy" "Copying root filesystem to ${target_partition} with rsync"
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info "fs copy" "This will take quite a while. Please be patient!"
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rsync -ax / /mnt
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info "boot config" "Configuring boot from {$target_partition}"
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# rootdelay=5 is likely not necessary here, but seems to do no harm.
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cp /boot/cmdline.txt /boot/cmdline.txt.bak
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sed -i "s|root=\/dev\/mmcblk0p2|root=PARTUUID=${partition_unique_guid} rootdelay=5|" /boot/cmdline.txt
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info "boot config" "Commenting out old root partition in /etc/fstab, adding new one"
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# These changes are made on the new drive after copying so that they
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# don't have to be undone in order to switch back to booting from the
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# SD card.
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sed -i '/mmcblk0p2/s/^/#/' /mnt/etc/fstab
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echo "/dev/disk/by-uuid/${target_partition_uuid} / ext4 defaults,noatime 0 1" >> /mnt/etc/fstab
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info "boot config" "Ok, your system should be ready. You may wish to check:"
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info "boot config" " /mnt/etc/fstab"
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info "boot config" " /boot/cmdline.txt"
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info "boot config" "Your new root drive is currently accessible under /mnt."
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info "boot config" "In order to restart with this drive at /, please type:"
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info "boot config" "sudo reboot"
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