Re: echo -n "" != perl open/close

[Thomas Bushnell, n/BSG]

echo -n ""  

will issue a zero-length write syscall, which forces a file update.

A perl open/close with no writes is not the same thing, because it
doesn't do any writes.  Open for writing does not touch a file or its
metadata in any way.  Perl isn't doing anything clever...

So `echo -n "" > foo' amounts to a sequence of open/write/close,
whereas the perl in question is only open/close.  The activities that
force the cache callback checks are associated with doing the write.

Thomas