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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 ?

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3 Answers 3

up vote 7 down vote accepted

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


chown "${SUDO_UID}:${SUDO_GID}" dir
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Nice anwser, with the solution AND some additional infos. –  e-satis Nov 30 '09 at 13:43
Using the UID/GID is the best solution, as it is possible to have multiple UIDs with the same username. –  duffbeer703 Nov 30 '09 at 13:46
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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.

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SUDO_USER can be overwritten by the user.

 $ SUDO_USER='lala' sudo SUDO_USER='test' printenv | grep USER

You should use 'who am i' or 'logname' to get the original username

toto:~$ SUDO_USER='lala' sudo SUDO_USER='test' logname             
toto:~$ SUDO_USER='lala' sudo SUDO_USER='test' who am i
toto   pts/4        Jan 23 15:13 (:0.0)

Coming from http://stackoverflow.com/questions/4598001/how-do-you-find-the-original-user-through-multiple-sudo-and-su-commands

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