Fastboot commandline utilisation as per eLinux.org is shown below.
$ fastboot -h
usage: fastboot [ <option> ] <command>
commands:
update <filename> reflash device from update.zip
flashall flash boot + recovery + system
flash <partition> [ <filename> ] write a file to a flash partition
erase <partition> erase a flash partition
getvar <variable> display a bootloader variable
boot <kernel> [ <ramdisk> ] download and boot kernel
flash:raw boot <kernel> [ <ramdisk> ] create bootimage and flash it
devices list all connected devices
reboot reboot device normally
reboot-bootloader reboot device into bootloader
options:
-w erase userdata and cache
-s <serial number> specify device serial number
-p <product> specify product name
-c <cmdline> override kernel commandline
-i <vendor id> specify a custom USB vendor id
update: What does update.zip need to look like
In general, fastboot flashes only .img files.
The update.zip generally consists of .img files which will be flashed to the particular partition. A typical update.zip file to flash via fastboot will have following files and more
boot.img
recovery.img
system.img
userdata.img
radio.img
etc...
flashall: Where do the flash boot + recovery + system come from, what
format, etc.
flashall will flash the system.img, boot.img & recovery.img in the current/PATH folder. These images can be obtained from the update.zip mentioned above.
boot: What is the format of <kernel> and what is the <ramdisk> option
In fastboot boot, the <kernel> format is an .img file. I am not sure of the <ramdisk> option. My guess would be to boot a kernel with a modified ramdisk without altering the built kernel (I am not a developer, sorry).
This is what I have learnt fiddling with Nexus phones. Others can correct any obvious errors in the write up.
