Re: Grep --directories option (POSIX)

[Paul Eggert]

Stepan Kasal <kasal@math.cas.cz> writes:

> The exception are sytems where a file can be ``text file'' and directory
> at once.  (I haven't heard about any such system except GNU/Hurd.)

But even on (say) Solaris, a directory might be a text file, since its
contents might happen to be valid text.  It's not likely, but I assume
it's possible, at least on some of the filesystem types (UFS, HSFS,
whatever).  And if a Hurd system is exporting a directory to Solaris
via NFS or CIFS, the Solaris 'grep' will indeed see a directory that
is a text file.

Unless an OS can guarantee that no directory will ever be a text file,
we can't make --directories=skip the default on that OS.  And since we
know of at least one OS where directories can be text files, we can't
make --directories=skip the default everywhere while conforming to
POSIX; of the current options, only --directories=read conforms to
POSIX everywhere.