On Tue, 3 Oct 2017, Chet Ramey wrote:
> On 10/3/17 4:14 PM, Mikulas Patocka wrote: > > > > > > On Sun, 1 Oct 2017, Chet Ramey wrote: > > > >> On 9/30/17 4:20 AM, Mikulas Patocka wrote: > >> > >>> Is there some reason why do we need to check if $OLDPWD is a real > >>> directory? dash and ksh accept the $OLDPWD variable, but don't poke it > >>> with the stat syscall. zsh clears $OLDPWD. > >> > >> It makes no sense to inherit it if it doesn't name a directory (or > >> "pathname" in the Posix standard), other than the sort of lazy evaluation > >> that will prevent your particular problem. > > > > Does something bad happen if we inherit $OLDPWD that points to a > > non-existing directory? Will some script malfunction because of it? > > `cd -' will fail, of course. That's where $OLDPWD gets used. And who > knows whether some script will fail? It's impossible to say. If $OLDPWD points to a non-existing directory, 'cd -' will fail. But if we clear $OLDPWD, 'cd -' will fail too (with just different message). Mikulas
