On Fri, 2020/07/10 05:39:59PM -0400, Giles Orr <gilesorr@gmail.com> wrote: | I love this list! I thought that '[ -w . ]' and '[ -w $PWD ]' were | practically equivalent. "Practically" means, in this case, "almost." | But not quite - and the difference is the solution to the problem. It's a very important, though sometimes subtle, concept in unix-land that there are multiple names for just about anything. Here, obviously, $PWD is a variable substitution equivalent to /some/path, which likely existed at some point, but may or may not exist now. The directory "." always (I think) exists, because a process always has a current directory open. (Hmmm, but opendir(".") might not work?) The other canonical example is "how do I remove a file that starts with -?". The key to that of course is the multiple names thing "-file" (which looks like an option string) is the same as "./-file" (which doesn't). Once you understand that, the world opens up :-) Of course, most times "rm -- -file" works but I'm old enough (uh, I mean I've read about the history of unix) to know that -- didn't always exist. Cheers John