Hi,

I was trying to install a program , which creates "on the fly " scripts containing the following line.

/bin/su - username -c "set " > /tmp/env.out

The installation program uses the script to do various environment checks.
When the above command runs "set " via su , it does not detect all the environment variables, su as a shortcut i moved su to su.old and made a new su command containing the lines required by the installation to continue.

But when i moved back su.old to su, I am unable to do
su - root,
It gives

su: Authentication failure
Sorry.


However If I do
sudo su - root
it works . I am using Gentoo with kernel 2.6 (2.6.10-gentoo-r6)


Thks for your help
Ali

I am not sure, but probably you lost the SETUID bit when you copying it around. It must be set as:

-rwsr-xr-x 1 root root 27648 2005-09-10 02:56 /bin/su

The command to set the SETUID bit is "chmod u+s /bin/su".

Thank you for the help, it worked, now if I go back to my original problem,

a)

/bin/su - username -c "set " > /tmp/env0.out

b)

su - username
set > tmp>env1.out

Why env1.out and env0.out are different ?

Thks
Ali

Because the initialization scripts (profile, bashrc, and others) have conditional statements that detects an interactive shell from a non-interactive one.

For example, in a non-interactive shell you may skip several things that are not used in such shell, things like a full featured prompt, alias commands, history list, and so. A non-interactive shell may be used to read/execute another script shell. Doing this, you save time in initializing such shell and start the script as soon is possible.

This logic may left out some important variable your particular application is in need, so you have to move it from the conditional section to the static/fixed section.