cros flash is a script to update a ChromiumOS device with an image, or to copy image onto a removable device (e.g. a USB drive) or save it as a file.
cros flash utilizes the devserver to download images and/or generate payloads.
When updating a ChromiumOS device, cros flash relies on an SSH connection to talk to the device (which is enabled in test images). cros flash assumes that the device is NOT capable of initiating an SSH connection to your workstation, allowing it to be used in a more restricted/secured network environment.
cros flash downloads artifacts and generates payloads.If your device is currently running a non-test image, you will need to use a USB stick to image the device with a test image first (see developer guide).
cros flash xBuddy/devserver to download the files. Devserver currently only runs in the chroot.cros flash <device> <image>
<device>: Required. ssh://IP[:port] of your ChromiumOS device, usb://path/to/removable/device, or file://path/to/a/file<image>: Optional. Can be a path to an image, an xBuddy path, a payload directory, or simply latest for latest locally-built image. Defaults to latest.[::1]:2222 instead of ::1:2222, as the port number is optional, and this prevents syntax ambiguity.For example, to update the device with the latest locally-built image, you can use the shortcut latest:
cros flash ssh://${DUT_IP} latest
or simply:
cros flash ssh://${DUT_IP}
To use a locally-built test image:
cros flash ssh://${DUT_IP} xbuddy://local/amd64-generic/R78-12450.0.0/test
To specify a local image by path:
cros flash ssh://${DUT_IP} path/to/image
To download the latest canary image:
cros flash ssh://${DUT_IP} xbuddy://remote/amd64-generic/latest-canary
Note: external developers will not be able to download non-public remote images. If you are prompted to confirm due to board mismatch, simply type ‘yes’ to proceed.
You can replace ssh://${DUT_IP} in the above examples with usb://device/path or usb:// to copy the image onto a removable device. However, you have to specify the board to use.
cros flash usb:// ${BOARD}/latest cros flash usb:///dev/sdc path/to/image
Finally, if you just want to look at the image you are installing (using mount_gpt_image.sh) or save the file for later, you can use file:// to save it to a file of your choice e.g.
cros flash file://path/to/save/image.bin path/to/image
Device can be ssh://hostname[:port] or hostname[:port]. Port number is the SSH port to use to connect to your device (defaults to 22).
Note: If you use
cros flashto install a non-test image,cros flashwill not be able to confirm that the device has rebooted successfully after the update. Also, you will not be able to usecros flashto reimage again becausecros flashrelies on being able to ssh into the device. You will need to use a USB stick to image your device.
Device can be usb://path/to/removable/device or usb://. If a device path is specified, cros flash will check if the device is indeed removable. If no path is given, the user will be prompted to choose from a list of removable devices.
Note that auto-mounting of USB devices should be turned off as it may corrupt the disk image while it's being written.
Please see the xBuddy documentation for more information on the format of xBuddy paths.
cros flash your pre-generated update payloads directly if you pass a payload directory as <image>:
cros flash ${DUT_IP} path/to/payload/directory
cros flash looks for update.gz and/or stateful.tgz in the payload directory and uses them to update the device.
cros flash can be used to test ChromiumOS update process without rebooting using option --no-reboot. This is useful when testing the update UI repeatedly.
cros flash --no-reboot ssh://${DUT_IP} path/to/image
cros flash is in the chromite repo. The script is chromite/cli/cros/cros_flash.py. The source is available here.
Make sure that update-engine service on device is running. If not:
# On the device start update-engine