Are there any legal paths in POSIX that cannot be associated with a file, regular or irregular? That is, for which
test -e "$LEGITIMATEPOSIXPATHNAME" cannot succeed?
Clarification #1: pathnames
By "legal paths in POSIX", I mean ones that POSIX says are allowed, not ones that POSIX doesn't explicitly forbid. I've looked this up, and the are POSIX specification calls them character strings that:
- Use only characters from the portable filename character set
- Do not begin with
- Have length between 1 and NAME_MAX, a number unspecified for POSIX that is not less than 14.
POSIX also allows that filesystems will probably be more relaxed than this, but it forbids the characters NUL and
/ from appearing in filenames. Note that such a paradigmatically UNIX filename as
lost+found isn't FPF, according to this def. There's another constant PATH_MAX, whose use needs no further explanation.
The ideal answer will use FPFs, but I'm interested in any example with filenames that POSIX doesn't expressly forbid.
Clarification #2: impossibility
Obviously, pathnames normally could be bound to a file. But UNIX semantics will tell you that there are special places that couldn't normally have arbitrary files created, like in the
/dev directory. Are any such special places stipulated in POSIX? That is what the question is getting after.