In a bash script executed on boot, how do I get the username of the user just logged-in? - bash

Question

I need to execute a bash script on boot.
To do so I created a file
/etc/init.d/blah
I edited it and added the following lines
#! /bin/sh
# /etc/init.d/blah
touch '/var/lock/blah'
username1=$(id -n -u)
username2=$(whoami)
touch '/var/lock/1'${username1}
touch '/var/lock/2'${username2}
exit 0
The script is execute with root privileges (which is what I need because I have to use mount inside this script) .. but the problem is that I also need to know the username of the user who has just logged-in beacuse my goal is to mount a certain folder to a certain mount-point depending on the username, like
mount -o bind /home/USERNAME/mount-point /media/data/home/USERNAME/to-be-mounted
Going back to the boot script, if I do
sudo update-rc.d blah defaults
and then reboot and log-in with my username (let's say john) both ways to get username in my script produce root in fact I've got 3 files
/var/lock/blah
/var/lock/1root
/var/lock/2root
So, how can I get the username of the user who just logged-in? (john in my example)
EDITED:
I solved in this way:
1. I created a .desktop file for each user I need to perform automount on boot to autostart a script on boot (I'm on LXDE) and put it on /home/{username}/.config/autostart
[Desktop Entry]
Type=Application
Exec=bash "/path/to/mount-bind.sh"
2. I stored in that path a bash script called mount-bind.sh and made it executable:
#!/bin/bash
_username=$1
if [[ -z "${_username}" ]]; then
_username="$(id -u -n)"
fi
mkdir -p "/home/${_username}/mount-folder"
sudo mount -o bind "/media/data/home/${_username}/mount-folder" "/home/${_username}/mount-folder"
exit 0
3. I added the following line to /etc/sudoers
%nopwd ALL=(ALL) NOPASSWD: /bin/mount
4. I created the nopwd group and added to it all the users I need
In his way after login I can mount the path under the user home.
Problem with this method is that I have to create the desktop file for each new user and add him/her to nopwd, but it works.
Any further improvement is welcome! :)

Answer 1

I think you should move from a boot time init script to a script executed at login time under the logged-in user. To allow this, you should look into ways to allow your users to execute the mount command you need. Depending on what you are trying to achieve, one of the following methods may help you:
Assuming you are on Linux or some other UNIX with a similar feature, add the mountpoint to /etc/fstab with the user option, allowing normal users to mount the entry.
Execute mount through sudo with a suitably narrow sudoers configuration as to not allow users to execute any mount commands.
Write a suid-root program in c which executes the required mount commands when called. This however is very tricky to get right without creating gaping security holes.

Answer 2

Login does not happen at boot time. You cannot foretell which user is going to log in when booting.

Answer 3

Try Exporting the logindetails and use it.
export username2=$(whoami)