You can use
admin show ddl to view the current job of adding an index or the running DDL jobs.
As for viewing DDL jobs, you can also use two other commands as follows:
admin show ddl jobs: to view all the results in the current DDL job queue (including tasks that are running and waiting to run) and the last ten results in the completed DDL job queue
admin show ddl job queries 'job_id' [, 'job_id'] ...: to view the original SQL statement of the DDL task corresponding to the
job_idonly searches the running DDL job and the last ten results in the DDL history job queue