User name before sudo

Question

I got a script rquiring sudo, but the script must set parameters according to the original user, such as:

chown "${USER}:${USER}" dir

If I set it under sudo, I just end up with "chmod root:root", which doesn't help.

How can I do that ?

Answer 1

The environment variable SUDO_USER should work as a replacement for USER.

Since you are setting the ownership to USER:USER I assume there is always a group with the same name as the user? A more strict solution might otherwise be to use SUDO_UID and SUDO_GID.

Two possible solutions would then be:

chown "${SUDO_USER}:${SUDO_USER}" dir

or

chown "${SUDO_UID}:${SUDO_GID}" dir

Answer 2

You can use the SUDO_USER variable:

sudo bash -c 'echo $SUDO_USER'

From the sudo man page:

if sudo is run by root and the SUDO_USER environment variable is set, sudo will use this value to determine who the actual user is. This can be used by a user to log commands through sudo even when a root shell has been invoked.