Without fully understanding the logic you're trying to implement, some comments on the first script, which seems to do what I think you want to be done:
- the exit 1 should come before the fi in all the else branches (unless you want the script to unconditionally exit with error code and never reach further commands).
- you might want to exit with the error code encountered when your command failed.
- the trap command should be executed early in the script, e.g. right after the exec redirection command.