每次重启wsl的时候，hadoop的fs都连不上了！！！
$ hadoop fs -ls /
-ls: java.net.UnknownHostException: master
Usage: hadoop fs [generic options]
[-appendToFile ... ]
[-cat [-ignoreCrc] ...]
[-checksum ...]
[-chgrp [-R] GROUP PATH...]
[-chmod [-R] PATH...]
[-chown [-R] [OWNER][:[GROUP]] PATH...]
[-copyFromLocal [-f] [-p] [-l] [-d] [-t ] ... ]
[-copyToLocal [-f] [-p] [-ignoreCrc] [-crc] ... ]
[-count [-q] [-h] [-v] [-t []] [-u] [-x] [-e] ...]
[-cp [-f] [-p | -p[topax]] [-d] ... ]
[-createSnapshot []]
[-deleteSnapshot ]
[-df [-h] [ ...]]
[-du [-s] [-h] [-v] [-x] ...]
[-expunge]
[-find ... ...]
[-get [-f] [-p] [-ignoreCrc] [-crc] ... ]
[-getfacl [-R] ]
[-getfattr [-R] {-n name | -d} [-e en] ]
[-getmerge [-nl] [-skip-empty-file] ]
[-help [cmd ...]]
[-ls [-C] [-d] [-h] [-q] [-R] [-t] [-S] [-r] [-u] [-e] [ ...]]
[-mkdir [-p] ...]
[-moveFromLocal ... ]
[-moveToLocal ]
[-mv ... ]
[-put [-f] [-p] [-l] [-d] ... ]
[-renameSnapshot ]
[-rm [-f] [-r|-R] [-skipTrash] [-safely] ...]
[-rmdir [--ignore-fail-on-non-empty] ...]
[-setfacl [-R] [{-b|-k} {-m|-x } ]|[--set ]]
[-setfattr {-n name [-v value] | -x name} ]
[-setrep [-R] [-w] ...]
[-stat [format] ...]
[-tail [-f] ]
[-test -[defsz] ]
[-text [-ignoreCrc] ...]
[-touchz ...]
[-truncate [-w] ...]
[-usage [cmd ...]]
Generic options supported are:
-conf specify an application configuration file
-D define a value for a given property
-fs specify default filesystem URL to use, overrides 'fs.defaultFS' property from configurations.
-jt specify a ResourceManager
-files specify a comma-separated list of files to be copied to the map reduce cluster
-libjars specify a comma-separated list of jar files to be included in the classpath
-archives ,...> specify a comma-separated list of archives to be unarchived on the compute machines
The general command line syntax is:
command [genericOptions] [commandOptions]
暂时的解决方式如下：
看看ssh启动了没：
ps -e | grep ssh
没有的话重启一下
sudo service ssh restart
如果是这样就启动成功了：
$ ps -e | grep ssh 7999 ? 00:00:00 sshd
尝试重启一些filesystem
$ start-dfs.sh Starting namenodes on [master] master: ssh: Could not resolve hostname master: Name or service not known Starting datanodes Starting secondary namenodes [master] master: ssh: Could not resolve hostname master: Name or service not known
报这个错是因为core-site.xml写的和/etc/hosts中的不一致，改一下core-site.xml，路径是${HADOOP_HOME}/etc/hadoop/:
我把master改成localhost了。
再次重启：
$ start-dfs.sh Starting namenodes on [localhost] Starting datanodes localhost: datanode is running as process 8278. Stop it first. Starting secondary namenodes [master]
如果报这个错就先stop一下：
$ stop-all.sh WARNING: Stopping all Apache Hadoop daemons as yc in 10 seconds. WARNING: Use CTRL-C to abort. Stopping namenodes on [localhost] Stopping datanodes Stopping secondary namenodes [master] master: ssh: Could not resolve hostname master: Name or service not known Stopping nodemanagers Stopping resourcemanager
然后再次重启：
$ start-dfs.sh Starting namenodes on [localhost] Starting datanodes Starting secondary namenodes [master]
这样就可以了，最后看看hadoop fs可以启动没有：
hadoop fs -ls / Found 2 items drwxr-xr-x - yc supergroup 0 2021-12-09 09:39 /index drwxr-xr-x - yc supergroup 0 2021-12-08 20:24 /wordcount
ok！
