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I saw the following script, posted online, that was used during the hadoop installation process.

  sudo tar xzf hadoop-0.20.2.tar.gz
  sudo mv hadoop-0.20.2 hadoop
  sudo chown -R hadoop:hadoop hadoop

I do not quite understand. What does the 

    sudo chown -R hadoop:hadoop hadoop

do here? Thanks for the explanation.

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it CHange OWNer of hadoop directory and everything under it (-R) to hadoop:handoop (user:group). see the chown manual: linux.die.net/man/1/chown – LiuYan 刘研 Jun 24 '11 at 1:38
1  
The syntax of linux commands is always listed in the man page. You can look up what any command and it's options by pulling up it's manual like this: man chown. – Caleb Jun 24 '11 at 6:37

1 Answer

up vote 6 down vote accepted

The command chown changes the ownership of files or directories.

The -R flag makes the command recursive, ie. it is applied to all the files and sub-directories inside given directory.

The string hadoop:hadoop changes the ownership (user:group).

The final hadoop is the name of the directory whose ownership is going to be changed.

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For the sake of completeness, I would only add that changing file/directory ownership requires root permissions, therefore the chown command is run with sudo. – Petr Uzel Jun 24 '11 at 5:58

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