gnome-session-quit to logout does not work when run as root with sudo

Question

I am running Ubuntu 14.04 and user name is pandya.

pandya@pandya-desktop:~$ gnome-session-quit

When above command run without being sudo (sudo su) in terminal, it successfully logs out.

---

But when running after sudo (as a root),

root@pandya-desktop:/home/pandya# gnome-session-quit

It gives error :

** (gnome-session-quit:3168): WARNING **: Failed to call logout: The name org.gnome.SessionManager was not provided by any .service files

So, because of being root, I tries to running command with sudo -u pandya gnome-session-quit to run command as a user pandya. But it gives same error.

Then I tries follwing to run as pandya:

root@pandya-desktop:/home/pandya# su pandya
pandya@pandya-desktop:~$ gnome-session-quit

** (gnome-session-quit:3269): WARNING **: Failed to call logout: The name org.gnome.SessionManager was not provided by any .service files

But it gives same error.

Hence, My question is: How to logout as a root? Because I want to put gnome-session-quit in sctipt which is to be run as root. (I don't want to kill forcefully process but want to normal logout prompt)

---

Further Specification:-

I have script which is to be run as root.

#! /bin/bash
....command to be executed.....
sudo -u pandya gnome-session-quit

Solution 1

I'm not entirely sure what you're trying to do but the reason the sudo command is failing is because you have started the X server as pandya and are not exporting pandya's environment variables that allow you to communicate with the running Gnome session.

So, this will allow you to kill your Gnome session:

sudo -E -u pandya gnome-session-quit

From man sudo:

-E, --preserve-env

Indicates to the security policy that the user wishes to pre‐ serve their existing environment variables. The security policy may return an error if the user does not have permis‐ sion to preserve the environment.

---

If you want to have a script that runs some commands as root and then want it to be able to log you out, you can do it as follows:

1. Create the script, without sudo for the privileged commands but with sudo for the logout. For example:

   #!/bin/bash
   
   apt-get install firefox
   sudo -E -u pandya gnome-session-quit
   

2. Run the script with sudo -E:

   sudo -E /path/to/script
   

The sudo -E script.sh ensures that your env variables are available to the script and the sudo -E -u pandya ensures that they are passed on to the gnome-session-quit call.

Solution 2

I've created this script that does set the DBUS session variables from the gnome-session environment in case you want to logout other users/sessions:

How to restart Gnome-Shell from command line?

function logout() {
    local USERNAME
    export USERNAMES=( ) 
    while [ -n "$1" ]; do case "$1" in
        -* ) break ;;
        *) USERNAMES+=( "$1" ); shift ;;
    esac; done

    for USERNAME in "${USERNAMES[@]}"; do
        local SESSION_PID=$(pgrep -fu "$USERNAME" gnome-session|head -1)
        if [ -n "$SESSION_PID" ]; then
            (
                sudo -u "$USERNAME" cat "/proc/$SESSION_PID/environ" | xargs -0 -n 1 echo export
                echo "gnome-session-quit --logout $@"
            ) | sudo -u "$USERNAME" sh -;
        fi
    done
}

Comments

[Louis Matthijssen]

Have you tried sudo -i -u pandya gnome-session-quit? The -i will emulate a terminal exactly like the user will get.

[Pandya]

@LouisMatthijssen : It also gives same error!

[terdon]

Is your script going to be run by root or will you use it with sudo? There is a difference.

[terdon]

@LouisMatthijssen that won't work because the -i launches a new login shell, it does not give "a terminal exactly like the user would get" (that would be an interactive, non-login shell) but starts a new login shell instance.

[terdon]

@Pandya please clarify your situation. You have mentioned sudo su and sudo. Please edit your question and clarify exactly which commands you are using and exactly what your script is supposed to do. These details are very important. My suggestion will work if you run it as pandya, not if you are already inside a root shell. I assumed you would run your script as sudo script.sh.

[Pandya]

I run script with sudo -E so it logs out successfully.