sudo issue

[Karl Auer]

On Mon, 2016-08-01 at 12:25 +0200, Ralf Mardorf wrote:
> is there a way to set up sudo, that it is able to copy everything,
> when running a line such as
> 
>   sudo cp -rp /path/.foo /to/another/path/

With fully-qualified paths, the above will work fine. It's wildcards
that are causing problems for you.

The wildcard expansion happens on your command line, and the result is
passed to sudo. The permissions in force when the wildcard expansion
happens are yours, not root's. You as a non-privileged user can't "see"
everything in the path, so the expansion comes up empty.

Because ls does not try and fail to read any directories - it tries and
succeeds, but finds no such files, because it wan't passed them. That's
why the error message is "no such file" instead of "permission
denied". 

If you executed the exact same command without sudo, you would see
"permission denied", which would be a big clue :-)

Here is the same thing simplified:

kauer at kt:~$ sudo touch /root/blah.txt
kauer at kt:~$ sudo ls /root
blah.txt
kauer at kt:~$ ls /root/*.txt
ls: cannot access '/root/*.txt': Permission denied
kauer at kt:~$ sudo ls /root/*
ls: cannot access '/root/*': No such file or directory

You can work around this by passing the command to a new shell,
protected by quotes:

kauer at kt:~$ sudo sh -c "ls /root/*.txt"
/root/blah.txt

Regards, K.

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Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

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