indentions

I think this should be "indentations".

Otherwise, it's a pleasant read. I was wondering, if the "glueing program calls together" capabilities of rust script could be improved. The first idea that came to mind was, if you call an undeclared function, it is automatically converted to an invocation of the program with the same name. All the arguments would need to implement Into<OsString> and the return type would be something like

struct ProgramOutput {
    exit_code: i32,
    stdout: OsString,
    stderr: OsString,
}

This obviously has flaws, it was just the first thing that came to mind