launchd: ask user before performing tasks
Make launchd call this AppleScript. It displays a dialog with a timeout and calls a shell script if the user selected "Ok".

set timeoutInSeconds to 60
set abortOnTimeout to true

tell application (path to frontmost application as text)
    try
        set dialogResult to display dialog "Do you want to execute?" default button 2 giving up after timeoutInSeconds
        on error number -128
            return
    end try
end tell

if gave up of dialogResult and abortOnTimeout then
    return
end if

do shell script "/path/to/yourscript.sh"