How to make shell scrips executable in new guest account?

Question

I executed the following commands to set up a guest account.

sudo adduser guest 
sudo chmod g+w /home/guest
sudo chmod o-rwx /home/* 
sudo usermod -aG guest pi

Then I put two working self executable shell scrips in the guest Desktop folder.

I used "chmod +x /home/guest//Desktop/xx" to make them executable from my Pi group.

I logged into guest, double click on the.sh file I get the "Execute in terminal" button but when I click on it, the terminal opens with; "(sudo) password for guest:"

One script is for avrdude.

#!/bin/bash

sudo avrdude -c linuxgpio -F -p atmega328p -v -U flash:w:/home/pi/xxxx

The other is just a shutdown file;

#!/bin/bash

sudo shutdown -h now

Update with info from comments:
What I am trying to do is to limit the user to execute the two scripts by clicking on them only. They need to program hundreds of printed circuit boards with the first .sh file, then, when finished for the day shutdown the Pi with the second. I'm wondering if there is a way to set the permission (just on the two above .sh files) so they alone have sudo permissions and work as they do in my Pi home folder.

Answer 1

sudo is powerful enough to do what you want. You can just add a policy file for sudo in /etc/sudoers.d/. Just do it with:

rpi ~$ sudo visudo /etc/sudoers.d/010_guest-nopasswd

In the empty editor insert these two lines with the correct path, save them and quit the editor:

guest ALL = (root) NOPASSWD: /full/path/to/avrdude
guest ALL = (root) NOPASSWD: /sbin/shutdown

The (root) entry ensures that the program can only be executed with root rights and not with rights of another user.

Answer 2

You want two scripts, that are located in the Desktop folder to be executed only from the user guest. The user guest is logged in and starts the scripts by clicking it.

Set the owner of the script to guest:

sudo chown guest:guest script1.sh script2.sh

Then set the execute permission only for the owner.

sudo chmod 500 script1.sh script2.sh

The user root always can execute the scripts. If you want to prevent him from doing this. You have to test if the user is not equal to 'guest' and end the script before it can execute its work. But you can not keep the root from changing the permissions or the script content.

Example:

#!/bin/bash

if [[ "$USER" != "guest" ]] ; then return; fi 

sudo avrdude -c linuxgpio -F -p atmega328p -v -U flash:w:/home/pi/xxxx

See the answer of @Milliways if you are interested of password less sudo access. But if you grant sudo access to guest he/she can do everything.

I know a work around, but it is complex and I have not the time to explain it here completely. You can write a little program that is started by the root account (or by systemd at boot time). This program listens on a TCP port and if it gets a trigger and a password from your script is executes the avrdude or performs a shutdown. Depending on the command you send to it. Now your script have only to send the command over a tcp connection to a process the has root rights. And if you prepare scripts as described above, only the user guest can execute it.

EDIT: There is also an idea, that uses Unix signals with trap and kill statements in scripts. So you do not have to write programs. But you must know how Unix signals work and you need a method to inform the trigger script about the process id of the root scope scripts the should start avrdude or shutdown the system.