Various problems and solutions encountered when the C program accesses hadoop

Problem 1: After compilation is passed, the following error occurs during running:

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Hadoop @ springwater-Aspire-4743:/usr/local/hadoop/test $./test
Exception in thread "main" java. io. IOException: Mkdirs failed to create/my
At org. apache. hadoop. fs. ChecksumFileSystem. create (ChecksumFileSystem. java: 378)
At org. apache. hadoop. fs. ChecksumFileSystem. create (ChecksumFileSystem. java: 364)
At org. apache. hadoop. fs. FileSystem. create (FileSystem. java: 555)
At org. apache. hadoop. fs. FileSystem. create (FileSystem. java: 536)
Call to org. apache. hadoop. conf. fileSystem: create (Lorg/apache/hadoop/fs/Path; ZISJ) Lorg/apache/hadoop/fs/FSDataOutputStream;) failed!
Failed to open/my/t.txt for writing!

Hadoop @ springwater-Aspire-4743:/usr/local/hadoop/test $./test
Exception in thread "main" java. io. IOException: Mkdirs failed to create/my
At org. apache. hadoop. fs. ChecksumFileSystem. create (ChecksumFileSystem. java: 378)
At org. apache. hadoop. fs. ChecksumFileSystem. create (ChecksumFileSystem. java: 364)
At org. apache. hadoop. fs. FileSystem. create (FileSystem. java: 555)
At org. apache. hadoop. fs. FileSystem. create (FileSystem. java: 536)
Call to org. apache. hadoop. conf. fileSystem: create (Lorg/apache/hadoop/fs/Path; ZISJ) Lorg/apache/hadoop/fs/FSDataOutputStream;) failed!
Failed to open/my/t.txt for writing!

Cause analysis: the read and write permissions are insufficient.

Solution:

Sudo./test

However, there are new problems:

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Hadoop @ springwater-Aspire-4743:/usr/local/hadoop/test $ sudo./test
Environment variable CLASSPATH not set!
Environment variable CLASSPATH not set!
Failed to open/my/t.txt for writing!

Hadoop @ springwater-Aspire-4743:/usr/local/hadoop/test $ sudo./test
Environment variable CLASSPATH not set!
Environment variable CLASSPATH not set!
Failed to open/my/t.txt for writing!

 

Problem 2: sudo env found that I am in ~ /. The environment variable CLASSPATH defined in bashrc is not inherited by sudo.

So sudo./test will show that CLASSPATH is not defined

Solution:

In/etc/sudoers, modify:
Defaults env_reset
Is:
Defaults! Env_rese

 

 

Question 3: After I modify sudo chmod 777/etc/sudoers,

Another error occurs in sudo chmod 777/etc/sudoers:

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Springwater @ springwater-Aspire-4743:/etc $ sudo chmod 440 sudoers
Sudo: the mode of/etc/sudoers is 0777, which should be 0440
Sudo: no valid sudoers resource found. Exit
Sudo: Unable to initialize the policy plug-in

Springwater @ springwater-Aspire-4743:/etc $ sudo chmod 440 sudoers
Sudo: the mode of/etc/sudoers is 0777, which should be 0440
Sudo: no valid sudoers resource found. Exit
Sudo: Unable to initialize the policy plug-in

 

Solution:

Su root

Go to the root mode and modify the settings.