What does "sudo chown -R hadoop:hadoop hadoop" do?

Question

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.

Solution

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.

Comments

[LiuYan 刘研]

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

[tcoolspy]

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.

[Petr Uzel]

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.