mkdir -p through a dangling symlink

[Garrett Wollman]

<<On Mon, 30 Jun 2008 19:51:45 +0200, Kris Kennaway <kris at freebsd.org> said:

> Suppose you do this:
> gohan20# ln -sf /y/portbuild /var/portbuild
> gohan20# mkdir -p /var/portbuild/scripts
> mkdir: /var/portbuild: No such file or directory

> (because /y/portbuild doesn't exist yet).

> Is this the correct behaviour, or should mkdir -p be creating 
> /var/portbuild/ before failing?

This is the correct behavior.  The semantics of the -p option are
defined lexically on the arguments provided, not on the contents of
the filesystem.  See XCU page 635 lines 24488ff:

# For each dir operand that does not name an existing directory,
# effects equivalent to those caused by the following command shall
# occur:

#	mkdir -p -m $(umask -S),u+wx $(dirname dir) &&
#	mkdir [-m mode] dir

# where the -m mode option represents that option supplied to the original
# invocation of mkdir, if any.

(References are for the 2001 final published standard.)

-GAWollman