I am pretty new in Linux and I have a doubt related to the use of the chown command use.

If I have something like this:

chown -R root:root /usr/share/MyApplicationDirectory

What exactly mean?

I think that I am changing the owner of all directory and files content into MyApplicationDirectory assigning them to the root user

But why it specify: root:root and not only root?

Reading the documenation I have found that the syntax is

chown [optuion] [--] user[:group] file1 [file2 …]

So I think that the :root is the group. But why? exist a :root group also a root user?


Simply you can change "group" or not.

chown -R root:root /usr/share/MyApplicationDirectory

means only user root or someone in group root (most Linux systems, including Ubuntu, have a root group).

chown -R root /usr/share/MyApplicationDirectory

in this case group is unchanged.


Yes. The user:group syntax is optional. And the -R means recursive. The reason there is a root group and a root user, is you may not always want to use the root acccount, but rather, an "admin" account, and it but still be a member of the root group, able to perform superuser actions (Most config files are owned by root but have group write permissions). Likewise, a salesman called "bob" may want to chown some sales presentations to bob:sales, so his colleagues can access them.

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