printing user of subshell obtaining root via su -

Question

Can I print the username which is obtaining root access via su - on the root console upon obtaining root?

user1$ su -
password:

obtained root via user1
#

See here: http://stackoverflow.com/questions/4598001/how-do-you-find-the-original-user-through-multiple-sudo-and-su-commands. — Massimo, Mar 27 '16 at 00:11

score 2 · Accepted Answer · edited Mar 27 '16 at 20:13

Previously I recommend the script below... I found a better way! :) Just exec:

logname

Also, you can use $SUDO_USER, but doesn't work if you are using sudo su -
By the way, who am i is like who -m

This script also does the work:

#!/bin/bash
curpid=`awk '/^PPid:/{print $2}' /proc/$BASHPID/status`
ppui=`awk '/^PPid:/{print $2}' /proc/$curpid/status`
ppui=`awk '/^PPid:/{print $2}' /proc/$ppui/status`
uid=`awk '/^Uid:/{print $2}' /proc/$ppui/status`
name=`cat /etc/passwd | grep $uid | awk -F: '{print $1}'`
echo $name

Call it through .bash_profile if you are using login shells or .bashrc if using interactive non-login shells.

Great idea using `logname`. Sometimes it's difficult to see the simplest solution ;). — Jakub Pasoń, Mar 27 '16 at 10:09

Jakub Pasoń · Answer 2 · 2016-03-27T08:50:01.313

1

who am i|awk '{print "Obtained root via "$1}'

Add it to root's .bashrc to execute when you su.

You can also try

pstree -p -u |grep "$$"

to see the whole chain of processes with usernames. This could be useful if you have nested su with multiple users.

edited Mar 27 '16 at 08:50

answered Mar 27 '16 at 08:35

Jakub Pasoń

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do you mean 'who | awk ..." – mahatmanich Mar 27 '16 at 09:47
1

No, I mean exectly what I wrote. `who | awk` will not work, because it will display all users that are logged in. Invoking who with two parameters is a nice trick, which displays only information about user who owns your terminal (so the one you `su`-ed from). – Jakub Pasoń Mar 27 '16 at 09:55
Anyway, using logname, as suggested in another comment, seems to be the simplest solution. – Jakub Pasoń Mar 27 '16 at 10:04
`who am i` does not do anything on my debian system – mahatmanich Mar 27 '16 at 10:10
It works in OSX and Centos Linux. Maybe `who -m` works for you ? – Jakub Pasoń Mar 27 '16 at 10:12
`who -m` also leads to nothing `who` just gives me a single line with my user `who -a` gives me all users logged in ... – mahatmanich Mar 27 '16 at 10:15
Ok, so Debian's who is a little different then. Use `man who` on your system as a definitive guide :). – Jakub Pasoń Mar 27 '16 at 10:18
I am going with logname since that gives me the session username which is what I want! Thanks for your kind help! – mahatmanich Mar 27 '16 at 10:20

printing user of subshell obtaining root via su -

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