[hules]

Something that I particularly hate with shell scripting is that if you modify a shell script while it is executing, it will break the running instance: bash does not load the whole script on startup, it reads it line after line while executing it. I wonder why this stupid and dangerous behavior has never been changed.

[caymanjim]

This is not true. I'm not sure what you're seeing, but neither bash nor zsh behave like this in Linux or MacOS.

[effie]

GP is correct. Bash does not read and parse whole script on start, that would be slow. It is done when needed.

[ptspts]

Wrap the script with:if :; ...; fi; exit