additional comments / links
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Brennen Bearnes
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2 changed files with 50 additions and 17 deletions
23
README.md
23
README.md
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@ -1,13 +1,15 @@
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adafruit-pi-externalroot-helper
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Adafruit-Pi-ExternalRoot-helper
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===============================
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A shell script for configuring an external USB drive as root filesystem
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on a Raspberry Pi running Raspbian.
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on a Raspberry Pi running Raspbian. It's a companion to [Using an
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External Drive as a Raspberry Pi Root Filesystem][tutorial], which you
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should read first.
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Adafruit Learning System guide coming soon.
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Using adafruit-pi-externalroot-helper
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-------------------------------------
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usage
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-----
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First, read the [tutorial][tutorial].
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On a Raspberry Pi running Raspbian, with a USB-connected storage device you
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wish to use for your root filesystem:
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@ -18,12 +20,12 @@ wish to use for your root filesystem:
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...where `/dev/sda` is the external USB you wish to use for a root filesystem.
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credit where due and further reading
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------------------------------------
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Sources and Further Reading
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---------------------------
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This is mostly an implementation of the process outlined in paulv's
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[HOWTO: Move the filesystem to a USB stick][1] on the Raspberry Pi
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forums, with additional help from the following sources:
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This script is mostly an implementation of the process outlined in paulv's
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[HOWTO: Move the filesystem to a USB stick][1] on the Raspberry Pi forums, with
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additional help from the following sources:
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- The Arch Linux wiki, [GUID Partition Table][2] for what a GPT is and
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some `parted` commands.
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@ -49,3 +51,4 @@ Along with manual / info pages for:
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[5]: https://samhobbs.co.uk/2013/10/speed-up-your-pi-by-booting-to-a-usb-flash-drive
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[wp]: https://en.wikipedia.org/wiki/GUID_Partition_Table
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[6]: https://github.com/torvalds/linux/blob/10975933da3d65f8833d4ce98dcc2ecc63a695d6/init/do_mounts.c#L183
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[tutorial]: https://learn.adafruit.com/external-drive-as-raspberry-pi-root
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@ -1,5 +1,11 @@
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#!/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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@ -13,10 +19,13 @@ function print_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."
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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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@ -25,6 +34,7 @@ function bail() {
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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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@ -37,6 +47,7 @@ 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 -- $args
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@ -61,7 +72,7 @@ do
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done
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if [[ ! -e "$target_drive" ]]; then
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bail "Target drive ${target_drive} must be an existing device (use -d /dev/foo to specify)"
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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 ${target_drive}"
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@ -74,12 +85,21 @@ then
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exit
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fi
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info "dependencies" "Installing gdisk, rsync, and pv."
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apt-get install gdisk rsync pv
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export target_partition="${target_drive}1"
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info "dependencies" "Installing gdisk, rsync, and pv."
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# Both of these 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 "${target_drive}" mkpart primary ext4 0% 100%
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@ -91,6 +111,12 @@ info "fs id" "Getting UUID for target partition"
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export target_partition_uuid=$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 /dev/sda | grep 'Partition unique GUID:' | awk '{print $4}'`
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info "fs id" "Target partition UUID: ${target_partition_uuid}"
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@ -99,17 +125,21 @@ 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}"
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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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cat /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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