gcloud storage objects compose

NAME
gcloud storage objects compose - concatenate a sequence of objects into a new composite object
SYNOPSIS
gcloud storage objects compose SOURCE [SOURCE …] DESTINATION [--additional-headers=HEADER=VALUE] [--delete-source-objects] [--clear-custom-contexts     | --custom-contexts=[CUSTOM_CONTEXTS_KEYS_AND_VALUES,…]     | --custom-contexts-file=CUSTOM_CONTEXTS_FILE] [--if-generation-match=GENERATION --if-metageneration-match=METAGENERATION] [--retain-until=DATETIME --retention-mode=RETENTION_MODE] [GCLOUD_WIDE_FLAG …]
DESCRIPTION
gcloud 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 storage objects compose gs://bucket/a.txt gs://bucket/b.txt gs://bucket/target.txt

Contexts are merged from source objects on the composed object by default. However, the following command overwrites custom contexts on composed object: 

gcloud storage objects compose gs://bucket/a.txt gs://bucket/b.txt gs://bucket/target.txt --custom-contexts=key1=value1,key2=value2

The following command creates a new object target.txt by concatenating a.txt and b.txt, and deletes the source objects after a successful composition: 

gcloud storage objects compose gs://bucket/a.txt gs://bucket/b.txt gs://bucket/target.txt --delete-source-objects
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.
--delete-source-objects
If set, the source objects will be deleted after a successful composition. Note that this deletion bypasses the soft delete policy if configured on the bucket.
OBJECT CONTEXTS FLAGS
Group that allow users to handle object contexts.

At most one of these can be specified:

--clear-custom-contexts
Clears all custom contexts on objects.
--custom-contexts=[CUSTOM_CONTEXTS_KEYS_AND_VALUES,…]
Sets custom contexts on objects. The existing custom contexts (if any) would be overwritten.
--custom-contexts-file=CUSTOM_CONTEXTS_FILE
Path to a local JSON or YAML file containing custom contexts one wants to set on an object. For example:

1. The following JSON document shows two key value pairs, i.e. (key1, value1) and (key2, value2): 

  {
    "key1": {"value": "value1"},
    "key2": {"value": "value2"}
  }

2. The following YAML document shows two key value pairs, i.e. (key1, value1) and (key2, value2): 

  key1:
    value: value1
  key2:
    value: value2

Note: Currently object contexts only supports string format for values.

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 variant is also available: 
gcloud alpha storage objects compose