bash - how to test, if a script is exececuted with sudo ?

almatic · 10-18-2008, 04:29 PM

Hi,

as title says, how can I test, if a script is exececuted with sudo ?
Testing for root is easy, but what about those nasty ubuntu users ?

if {what here ??};then
echo "I was executed with sudo"
else
echo "I was not executed with sudo"
fi

keefaz · 10-18-2008, 04:44 PM

Does it work on your system ?

Code:

if [ ! -z "$SUDO_USER" ]; then
    echo "I was executed with sudo"
fi

almatic · 10-18-2008, 05:30 PM

no, unfortunately not. I have no variable SUDO_USER set. Where is it set normally ? Is it set on a default ubuntu system ?

jcookeman · 10-18-2008, 06:07 PM

Indeed

Code:

$ cat /etc/issue
Ubuntu 8.04.1 \n \l
$ cat sudo.sh
#!/usr/bin/env sh
echo $SUDO_USER
$ sudo ./sudo.sh
jcook

lwasserm · 10-18-2008, 07:36 PM

Quote:

Originally Posted by almatic

Hi,

as title says, how can I test, if a script is exececuted with sudo ?
Testing for root is easy, but what about those nasty ubuntu users ?

if {what here ??};then
echo "I was executed with sudo"
else
echo "I was not executed with sudo"
fi

Are you meaning to distingusish between a script run with sudo vs. a script run by a "real" root or superuser? The man page for sudo says:

Quote:

... sudo allows a permitted user to execute a command as the superuser or another user, as specified in the sudoers file. The real and effective uid and gid are set to match those of the target user as specified in the passwd file...

so I'm not sure you can do a simple test. On a system using sudo there often is no way for a real superuser to even log on.

It's usually recommended to avoid using environment variables like $UID for security purposes because they are easily changed by the user. Use something like the id command instead.

dwhitney67 · 10-19-2008, 11:06 AM

I was not aware that running as 'sudo' in Ubuntu was any different than running as 'sudo' in Fedora (or any other distro).

If you want to verify if a user has superuser privileges, then try:

Code:

if [ `id -u` -eq 0 ]
then
        echo "Ah, welcome O' Mighty One."
else
        echo "No grunt users allowed beyond this point!"
        exit 1
fi

almatic · 10-19-2008, 03:36 PM

yes, you're right, there is no need to test for sudo. I thought it wouldn't change the uid on ubuntu, but it does. I should have read the manpage better ...