bash — the command shell

Distinguish bash invocation options from set options and shopt settings: these are separate interfaces, not one flat option list. bash script.sh runs a script in another shell. source script.sh runs it in the current one and can change its variables or directory.

Use set -o to inspect shell options and shopt to inspect additional settings. These diagnostic invocations do not change the mode. Before copying settings from an example, identify which shell should receive them.