A question about permissions in Linux

problem Description: a user groupTestGroupto the directory/tmp/Testhave read, write, execute permission; user group test users to directory The Chinese part has only read permission, and the owner and owner of the file isRootwhen the user belonging to the user group test Groupafter the testuser logs onwithVimafter forced editing, the owner and owner of the file becomes testuser and the TestGroup , at this timeEchocan't write.

Verification process:

1.First, create a user as rootTestUser and Users group Testgroupafter, so that testuser with Testgroup as an additional group,againCreate a validation directory for/tmp/test, and change the group of directories to Testgroup and enable the group to have write permissions as follows.

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2, in this directory as the root user to create the files testfile, note that at this time the file testfile the group does not have write permissions.

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3. Switch user to TestUser, and write the character "abc" to/tmp/test/testfile with Echo (because there is no write permission, it cannot be written).

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4, testuser with Vim Open and write "abc", forcibly save exit.

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The VIM editor prompts you with the following information:

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Force write Save exit:

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5, at this time to view the contents of the file as "ABC", and the document is the owner and the group actually become testuser.

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Extended Thinking : If the user group Testgroup to this directory/tmp/test/testfile there is no write permission, only read and Execute permissions. Neither Vim nor Echo can be written.

See this blog post of the vast number of netizens can try to verify the above process, I hope there are cattle people on this phenomenon can enlighten one or two.

Note: This verification process is based on CentOS 6.7 validation.

This article is from the "Roadtoom" blog, make sure to keep this source http://flyalways.blog.51cto.com/7680670/1726570

A question about permissions in Linux