flash script (OnePlus 7T tested)

flash.sh

#!/bin/bash

indir=${PWD}

clean_preinstall () {
	for part in system system_ext odm product vendor; do
		fastboot erase ${part}
	done
}

clean_postinstall () {
	for part in userdata metadata; do
		fastboot erase ${part}
	done
}

flash_rom () {
	for img in boot dtbo odm product system system_ext \
		vbmeta vbmeta_system vendor; do
		if [ ! -f "${indir}/${img}.img" ]; then
			echo "XXX image ${indir}/${img}.img not found!"
			exit 1
		fi
	done

	for img in boot dtbo odm product system system_ext \
		vbmeta vbmeta_system vendor; do
		fastboot flash ${img} "${indir}/${img}.img"
	done
}

_help () {
	echo -e "\n+++ flash script +++

syntax:	flash.sh {action} [input directory]

where action can be one of

	u | update | -u		update the ROM
	c | clean  | -c		clean flash the ROM
		NOTE: ERASES ALL DATA!
	r | recovery | -r	flash recovery only

[input directory] is optionally the directory containing
the files, current working directory if not given.
"
}

[ -d "${2}" ] && indir="${2}"

case ${1} in
	u | update | -u )
		flash_rom
		fastboot reboot
	;;

	c | clean | -c )
		clean_preinstall
		flash_rom
		clean_postinstall
		fastboot reboot
	;;

	r | recovery | -r )
		if [ -f "${indir}/recovery.img" ]; then
			fastboot flash recovery "${indir}/recovery.img"
			fastboot reboot recovery
		else
			echo "XXX image ${indir}/recovery.img not found!"
		fi
	;;

	* )
		_help
	;;
esac