Shell Script to Toggle Between Two Commands

One good way of accomplishing this is for the script to create a blank "configuration file":

• The 1st time the script runs, it sees the file doesn't exist, creates it, and runs command1.
• The 2nd time the script runs, it sees the file does exist, deletes it, and runs command2.
• The 3rd time the script runs, it sees the file doesn't exist, creates it, and runs command1.
• The 4th time the script runs, it sees the file does exist, deletes it, and runs command2.

And so forth.

Here's a script that does that:

#!/bin/sh
# This shell script is PUBLIC DOMAIN. You may do whatever you want with it.

TOGGLE=$HOME/.toggle

if [ ! -e $TOGGLE ]; then
    touch $TOGGLE
    command1
else
    rm $TOGGLE
    command2
fi