题记

今天给服务器的mongodb数据库数据备份的时候发现了个错误 - Failed: error getting database names: command listDatabases requires authentication ，百度了一下也没搞到好的解决办法，最后自己研究了一下，发现了还是自己不太清楚 mongo 的指令，最后解决了。

过程

命令行运行:

mongodump

报错信息:

[root@VM_0_6_centos ~]# mongodump 
2020-02-29T16:56:52.186+0800	Failed: error getting database names: command listDatabases requires authentication

解决

搜索的过程就不再赘述，直接上解决的过程

命令行输入求助：

mongodump --help

打印信息：

Usage:
  mongodump <options>

Export the content of a running server into .bson files.

Specify a database with -d and a collection with -c to only dump that database or collection.

See http://docs.mongodb.org/manual/reference/program/mongodump/ for more information.

general options:
      --help                                                print usage
      --version                                             print the tool version and exit

verbosity options:
  -v, --verbose=<level>                                     more detailed log output (include multiple times for more verbosity, e.g. -vvvvv, or
                                                            specify a numeric value, e.g. --verbose=N)
      --quiet                                               hide all log output

connection options:
  -h, --host=<hostname>                                     mongodb host to connect to (setname/host1,host2 for replica sets)
      --port=<port>                                         server port (can also use --host hostname:port)

authentication options:
  -u, --username=<username>                                 username for authentication
  -p, --password=<password>                                 password for authentication
      --authenticationDatabase=<database-name>              database that holds the user's credentials
      --authenticationMechanism=<mechanism>                 authentication mechanism to use

namespace options:
  -d, --db=<database-name>                                  database to use
  -c, --collection=<collection-name>                        collection to use

uri options:
      --uri=mongodb-uri                                     mongodb uri connection string

query options:
  -q, --query=                                              query filter, as a JSON string, e.g., '{x:{$gt:1}}'
      --queryFile=                                          path to a file containing a query filter (JSON)
      --readPreference=<string>|<json>                      specify either a preference name or a preference json object
      --forceTableScan                                      force a table scan

output options:
  -o, --out=<directory-path>                                output directory, or '-' for stdout (defaults to 'dump')
      --gzip                                                compress archive our collection output with Gzip
      --repair                                              try to recover documents from damaged data files (not supported by all storage engines)
      --oplog                                               use oplog for taking a point-in-time snapshot
      --archive=<file-path>                                 dump as an archive to the specified path. If flag is specified without a value, archive
                                                            is written to stdout
      --dumpDbUsersAndRoles                                 dump user and role definitions for the specified database
      --excludeCollection=<collection-name>                 collection to exclude from the dump (may be specified multiple times to exclude
                                                            additional collections)
      --excludeCollectionsWithPrefix=<collection-prefix>    exclude all collections from the dump that have the given prefix (may be specified
                                                            multiple times to exclude additional prefixes)
  -j, --numParallelCollections=                             number of collections to dump in parallel (4 by default) (default: 4)
      --viewsAsCollections                                  dump views as normal collections with their produced data, omitting standard collections

其中有提示:

authentication options:
  -u, --username=<username>                                 username for authentication
  -p, --password=<password>                                 password for authentication

那么就输入指令

mongodump --username=<username> --password=<password>   

完美解决

2020-02-29T17:00:32.953+0800	writing admin.system.
2020-02-29T17:00:32.975+0800	done dumping admin.
2020-02-29T17:00:32.975+0800	writing admin.system.
2020-02-29T17:00:32.997+0800	done dumping admin.
2020-02-29T17:00:32.997+0800	writing tdata.
2020-02-29T17:00:32.997+0800	writing ***
2020-02-29T17:00:32.997+0800	writing ***
2020-02-29T17:00:32.997+0800	writing ***
2020-02-29T17:00:33.098+0800	done ***
2020-02-29T17:00:33.098+0800	writing ***
2020-02-29T17:00:33.098+0800	done dumping ***
2020-02-29T17:00:33.098+0800	writing ***
2020-02-29T17:00:33.099+0800	done ***
2020-02-29T17:00:33.099+0800	writing ***
2020-02-29T17:00:33.100+0800	done dumping ***
2020-02-29T17:00:33.163+0800	done dumping ***
2020-02-29T17:00:33.163+0800	done dumping ***
2020-02-29T17:00:33.169+0800	done dumping ***