无法找到或加载主类M - hadoop窗口 [英] Could not find or load main class M - hadoop windows

问题描述

我是hadoop的新手，我试图在windows 10上设置hadoop。我从Apache网站下载了hadoop 2.7.3 tar.gz版本。这些是我已经完成的步骤：

1. 将tar.gz解压缩到C：\ ---> C：\\ \\ hadoop


2. 创建并设置HADOOP_HOME环境变量为C：\ haddoop


3. 通过添加C：\ haddoop \\ \\ bin


4. 添加JAVA_HOME环境变量并将其设置为jdk主目录。

问题是，我执行的任何与Hadoop相关的命令都给了我以下错误：
$ b

错误：无法找到或加载主类M

例如，即使执行以下命令，我也会收到此错误： hadoop version

我在stackoverflow上阅读了很多相关文章，并尝试了不同的建议，比如更新hadoop-env.sh，hadoop-config.sh，重复整个集合启动过程多次。在这里的其他帖子似乎指的是处理特定类的错误，但是，我面对的错误不提供任何类名，它只是说类M.

我不确定问题是什么，而我所做的一切似乎都没有奏效。任何人都可以让我知道什么是错的，我怎么能解决这个问题？ 解决方案

这个问题可能与语法有关的系统用户名。在这种情况下，转到您的Hadoop目录并编辑/etc/hadoop/hadoop-env.cmd

在文件结尾处您会发现：

  set HADOOP_IDENT_STRING =％USERNAME％
  

将其更改为您想要的名称，但不包含空格，例如：

  set HADOOP_IDENT_STRING = myuser 
  

希望这会有所帮助

I am new to hadoop and I am trying to set up hadoop on windows 10. I downloaded the hadoop version 2.7.3 tar.gz from Apache website. These are the steps I have done:

1. Extracted the tar.gz into a folder in C:\ ---> C:\hadoop
2. Created and set the HADOOP_HOME environment variable to C:\hadoop
3. Updated the PATH environment variable by adding C:\hadoop\bin
4. Added the JAVA_HOME environment variable and set it to the jdk home folder.

The issue is that, any Hadoop related command I execute gives me the following error:

Error: Could not find or load main class M

For example, I get this error even on executing the following command:hadoop version

I read a lot of related posts on stackoverflow, and tried the different suggestions such as updating hadoop-env.sh, hadoop-config.sh, repeated the whole set up process multiple times. The other posts here seem to refer to errors that deal with specific classes, however, the error I face does not provide any class name, it just says class M.
I am not sure what the problem is, and nothing I do seems to work. Could anyone please let me know what is wrong and how I could solve this issue?

解决方案

The problem may be related to the syntax of your system username. In such case, go to your Hadoop directory and edit /etc/hadoop/hadoop-env.cmd

Near the end of the file you'll find:

set HADOOP_IDENT_STRING=%USERNAME%

change it to whatever name you want, but one NOT containing a space, eg.:

set HADOOP_IDENT_STRING=myuser

hope this will help

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