In CacheAdmin, there are two places that not completely showing the cmd usage message.
$ hdfs cacheadmin
Usage: bin/hdfs cacheadmin [COMMAND]
[-addDirective -path <path> -pool <pool-name> [-force] [-replication <replication>] [-ttl <time-to-live>]]
[-modifyDirective -id <id> [-path <path>] [-force] [-replication <replication>] [-pool <pool-name>] [-ttl <time-to-live>]]
[-listDirectives [-stats] [-path <path>] [-pool <pool>] [-id <id>]
[-removeDirectives -path <path>]
[-addPool <name> [-owner <owner>] [-group <group>] [-mode <mode>] [-limit <limit>] [-maxTtl <maxTtl>]
The command -listDirectives and -addPool are not showing completely, they are both lacking a ']' in the end of line.
In the CentralizedCacheManagement.md, there is also a similar problem. The page of CentralizedCacheManagement can also showed this, https://hadoop.apache.org/docs/r2.7.2/hadoop-project-dist/hadoop-hdfs/CentralizedCacheManagement.html