What is export for?
What is the difference between:
export name=value
and
name=value
export makes the variable available to sub-processes.
That is,
export name=value
means that the variable name is available to any process you run from that shell process. If you want a process to make use of this variable, use export, and run the process from that shell.
name=value
means the variable scope is restricted to the shell, and is not available to any other process. You would use this for (say) loop variables, temporary variables etc. An important exception to this rule is that if you define the variable while running a command, that variable will be available to child processes. For example
MY_VAR=yay node my-script.js
In this case MY_VAR will be available to the node process running my-script.
It's important to note that exporting a variable doesn't make it available to parent processes. That is, specifying and exporting a variable in a spawned process doesn't make it available in the process that launched it.