MacOS – Execute a BASH script… by double-clicking on it

Take the script that you created:

#!/bin/bash

echo "plugin L2TP.ppp">>/etc/ppp/options 
echo "l2tpnoipsec">>/etc/ppp/options

Save it in your home directory, or a 'scripts' directory inside your home directory, as l2tp.sh. Allow it to be executed(write this command in Terminal):

chmod 700 ~/path/to/l2tp.sh

To execute the file using sudo (root privileges):

Method #1. In Terminal type:

$ sudo ~/path/to/l2tp.sh

Method #2. Create a file run_l2tp.command with this contents:

sudo ~/path/to/l2tp.sh

Allow it to be executed:

chmod u+x run_l2tp.command

When you double-click run_l2tp.command and enter the password the l2tp.sh file will be executed with root privileges.

Some notes:

• On UNIX like systems, ~ is short for "my home directory".
• Chmod 700 will make the file executable only by you. For more information: see this Wikipedia page.
• typing 'sudo' before a command will execute the program using root privileges. Be careful when doing this, bad things can happen if you're not sure what you're doing.
• Obviously you can omit the /path/to if you saved this script directly in your home directory.

If you really want to make your old mac happy I would say the best thing is the SSD. It will make it feel faster than it was out of the box and that is because it is. A RAM upgrade isn't really necessary and I would suggest investing that money over into a new battery. If the unit hasn't been used in a good long while chances are your battery will be dead or inches away from death.

A new battery (directly from Apple) will be guarantied for a year and will give you a notebook to take with you (using an SSD instead of a HDD also gives you a few extra minutes in battery life.

CleanMyMac is not recommended! Instead install a new OS on the SSD and then using an external enclosure transfer the data via Migration Assistant. But always make sure you have a backup of your files.

Honestly I am more of a fan of keeping things fresh and installing 3PP programs fresh too and manually dragging over your documents, pictures, music, etc.