gcloud alpha storage objects compose

NAME
gcloud alpha storage objects compose - concatenate a sequence of objects into a new composite object
SYNOPSIS
gcloud alpha storage objects compose SOURCE [SOURCE …] DESTINATION [--additional-headers=HEADER=VALUE] [--if-generation-match=GENERATION --if-metageneration-match=METAGENERATION] [--retain-until=DATETIME --retention-mode=RETENTION_MODE] [GCLOUD_WIDE_FLAG …]
DESCRIPTION
(ALPHA) gcloud alpha storage objects compose creates a new object whose content is the concatenation of a given sequence of source objects in the same bucket. For more information, please see: composite objects documentation.

There is a limit (currently 32) to the number of components that can be composed in a single operation.

EXAMPLES
The following command creates a new object target.txt by concatenating a.txt and b.txt: 
gcloud alpha storage objects compose gs://bucket/a.txt gs://bucket/b.txt gs://bucket/target.txt
POSITIONAL ARGUMENTS
SOURCE [SOURCE …]
The list of source objects that will be concatenated into a single object.
DESTINATION
The destination object.
FLAGS
--additional-headers=HEADER=VALUE
Includes arbitrary headers in storage API calls. Accepts a comma separated list of key=value pairs, e.g. header1=value1,header2=value2. Overrides the default storage/additional_headers property value for this command invocation.
PRECONDITION FLAGS
--if-generation-match=GENERATION
Execute only if the generation matches the generation of the requested object.
--if-metageneration-match=METAGENERATION
Execute only if the metageneration matches the metageneration of the requested object.
RETENTION FLAGS
--retain-until=DATETIME
Ensures the destination object is retained until the specified time in RFC 3339 format.
--retention-mode=RETENTION_MODE
Sets the destination object retention mode to either "Locked" or "Unlocked". When retention mode is "Locked", the retain until time can only be increased. RETENTION_MODE must be one of: Locked, Unlocked.
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 alpha and might change without notice. If this command fails with API permission errors despite specifying the correct project, you might be trying to access an API with an invitation-only early access allowlist. This variant is also available: 
gcloud storage objects compose