Writing '...' switches from "writing shell code" to "writing a single-quoted string". It does not switch to "writing arbitrary text" (since that would give us no way to end the string!). You should always convert arbitrary text to "single-quoted string" format: most of the time it will stay the same, e.g. "google.com"; sometimes it needs escaping to prevent benign corruption, e.g. "I'm a little teapot"; in this case it needs escaping to prevent malicious code injection.