How to run a .sh file in terminal on login

When you set Terminal=true in the desktop file, the terminal window by default closes after the "the job has finished". An easy solution is to change your (terminal-) profile settings:

• open a terminal window, choose Profile Preferences
• choose "Title & Command" (at least that is what it is in Dutch, the second tab)
• in the section "when the command has finished" choose "keep terminal window open"

And of course, like you did, in the desktop file, set Terminal=true

Solution for Question --> "so I have a simple sh file I want to run whenever someone logs in. I tried adding it to startup applications."

Suppose path of your file is /home/foster/Desktop/script.sh

First make it executable by :

$ chmod +x /home/foster/Desktop/script.sh

Now just Add path of the script to file "/etc/rc.local" :

sh /home/foster/Desktop/script.sh
exit 0