gcloud beta compute instances tail-serial-port-output

NAME: gcloud beta compute instances tail-serial-port-output - periodically fetch new output from a virtual machine instance's serial port and display it as it becomes available
SYNOPSIS: gcloud beta compute instances tail-serial-port-output INSTANCE_NAME [--port=PORT] [--zone=ZONE] [GCLOUD_WIDE_FLAG …]
DESCRIPTION: (BETA) gcloud beta compute instances tail-serial-port-output is used to tail the output from a Compute Engine virtual machine instance's serial port. The serial port output from the instance will be printed to standard output. This information can be useful for diagnostic purposes.
EXAMPLES: To fetch new output from instance's serial port and display it, run:
gcloud beta compute instances tail-serial-port-output example-instance --zone=us-central1-b
POSITIONAL ARGUMENTS: INSTANCE_NAME

Name of the instance to operate on. For details on valid instance names, refer to the criteria documented under the field 'name' at: https://cloud.google.com/compute/docs/reference/rest/v1/instances
FLAGS: --port=PORT

Instances can support up to four serial port outputs, numbered 1 through 4. By default, this command will return the output of the first serial port. Setting this flag will return the output of the requested serial port.

--zone=ZONE

Zone of the instance to operate on. If not specified, you might be prompted to select a zone (interactive mode only). gcloud attempts to identify the appropriate zone by searching for resources in your currently active project. If the zone cannot be determined, gcloud prompts you for a selection with all available Google Cloud Platform zones.
To avoid prompting when this flag is omitted, the user can set the compute/zone property:
gcloud config set compute/zone ZONE

A list of zones can be fetched by running:
gcloud compute zones list

To unset the property, run:
gcloud config unset compute/zone

Alternatively, the zone can be stored in the environment variable CLOUDSDK_COMPUTE_ZONE.
GCLOUD WIDE FLAGS: These flags are available to all commands: --access-token-file, --account, --billing-project, --configuration, --flags-file, --flatten, --format, --help, --impersonate-service-account, --log-http, --project, --quiet, --trace-token, --user-output-enabled, --verbosity.
Run $ gcloud help for details.
NOTES: This command is currently in beta and might change without notice. These variants are also available:
gcloud compute instances tail-serial-port-output

gcloud alpha compute instances tail-serial-port-output