From: Maximilian Friedersdorff <max@friedersdorff.com>
Date: Thu, 11 Jul 2019 15:05:35 +0000 (+0100)
Subject: Write script to create live usb drive
X-Git-Url: https://git.friedersdorff.com/?p=max%2Fdisk_creator.git;a=commitdiff_plain;h=6adfa2b1372f09188a540cfd53dc3296086517aa

Write script to create live usb drive
---

diff --git a/disk_creator.sh b/disk_creator.sh
new file mode 100644
index 0000000..4dd8217
--- /dev/null
+++ b/disk_creator.sh
@@ -0,0 +1,114 @@
+#!/bin/bash
+
+# The name of the USB drive you want to create
+usb_drive="/dev/sdd"
+
+# The location of the linux distribution you want to use
+os_image="/mnt/os_images/xubuntu-18.04.2-desktop-amd64.iso"
+
+# Removing leading directory/folder name
+image_name="${os_image##*/}"
+# Removing the filename extension
+os_name="$(echo ${image_name%.*} | tr '-' ' ' | tr '_' ' ')"
+
+# Querying the block size, the logical size of entities on the USB drive
+block_size=$(cat /sys/block/${usb_drive#/dev/}/queue/hw_sector_size)
+
+# Calculate the size of the partition to hold the iso and boot loader.  Allow
+# 50MiB for the bootloader (this is way overkill).
+live_part_size="$(ls -l ${os_image} | 
+	awk -v block_size=${block_size} \
+	'{print (($5/block_size) + (50*1024*1024/block_size))}')"
+
+# Calculate the start of the 'usbdata' partition
+let usbdata_part_start="${live_part_size} + 2048 + 3*1024*1024*1024/${block_size}"
+
+# Find out the location of the linux kernel and the initramfs (initial ramdisk
+# file system) in the os image file. We need these locations later when 
+# configuring grub
+modprobe loop
+loop_dev="$(losetup --show -f ${os_image})"
+l_mount="$(mktemp -d)"
+mount -o ro "${loop_dev}" "${l_mount}"
+kernel="$(find ${l_mount} -iname *vmlinuz* -printf '%P\n')"
+initramfs="$(find ${l_mount} -iname *initr* -printf '%P\n')"
+umount "${l_mount}"
+rmdir "${l_mount}"
+losetup -d "${loop_dev}"
+
+if [ $(echo "${kernel}" | wc -l) -gt 1 ]; then
+	echo "Too many possible linux kernels found:"
+	echo $kernel
+fi
+
+if [ $(echo "${initramfs}" | wc -l) -gt 1 ]; then
+	echo "Too many possible initramfs found:"
+	echo $initramfs
+fi
+
+# Partition the usb drive. The partition listed first can be read by linux
+# and windows operating systems.  It is located at the 'end' of the drive
+# The partition listed second contains the operating system and boot loader,
+# it is located at the 'beginning' of the drive. The partition listed last fills
+# the space between the other two, and is used to record changes made to the 
+# operating system
+sfdisk "${usb_drive}" << EOF
+
+label: gpt
+
+start=$usbdata_part_start, type=11
+start=2048, size=$live_part_size, type=1
+type=20
+EOF
+
+# Format each partition with the relevant filesystem.
+mkfs.ntfs --fast -L usbdata "${usb_drive}1"
+mkfs.fat -F 32 "${usb_drive}2"
+mkfs.ext4 -q -F -L casper-rw "${usb_drive}3"
+
+# Create a temporary directory
+m_point=$(mktemp -d)
+
+# Mount the drive to the temporary directory, create some folders/directories,
+# copy the os image, and install the boot loader.
+mount "${usb_drive}2" "${m_point}"
+mkdir "${m_point}"/{boot,iso_boot}
+cp "${os_image}" "${m_point}/iso_boot" && sync
+grub-install "${usb_drive}" \
+	--target=x86_64-efi \
+	--efi-directory="${m_point}" \
+	--boot-directory="${m_point}/boot" \
+	--removable
+
+# Install the configuration file for the bootloader
+cat <<EOF> "${m_point}/boot/grub/grub.cfg"
+set timeout=10
+set default=0
+insmod loopback
+insmod all_video
+
+menuentry "Run ${os_name} Persistent, in RAM" {
+        loopback loop /iso_boot/${image_name}
+        set gfxpayload=keep
+        linux (loop)/${kernel} boot=casper iso-scan/filename=/iso_boot/${image_name} quiet splash persistent toram ---
+        initrd (loop)/${initramfs}
+}
+
+menuentry "Run ${os_name} - Persistent" {
+        loopback loop /iso_boot/${image_name}
+        set gfxpayload=keep
+        linux (loop)/${kernel} boot=casper iso-scan/filename=/iso_boot/${image_name} quiet splash persistent ---
+        initrd (loop)/${initramfs}
+}
+
+menuentry "Run ${os_name}" {
+        loopback loop /iso_boot/${image_name}
+        set gfxpayload=keep
+        linux (loop)/${kernel} boot=casper iso-scan/filename=/iso_boot/${image_name} quiet splash ---
+        initrd (loop)/${initramfs}
+}
+EOF
+
+# Clean up
+umount "${m_point}"
+rmdir "${m_point}"