Plash has only rudimentary support for shell scripts. You can get the shell to run a script file on startup with the --rcfile option. The "source file" command will run file as a script.

Each command in the script file must be terminated with a semicolon ";".

Plash doesn't accept any leading space in the script. This is a bug.

There is no error handling: if a command exits with a non-zero return code, it doesn't stop the script.

By default, the shell does not read any scripts on startup.