Re: creating directories through dependency

[Paul Smith]

On Tue, 2007-01-09 at 16:21 +0100, John Graham-Cumming wrote:
> Dave Korn wrote:
> > BTW, if you ever revise it, I noticed one minor omission in the
> > discussion of using the -p option to mkdir: as well as building a
> > whole path in one go, it also prevents mkdir from erroring out if the
> > destination dir already exists, meaning that you don't have to use
> > "-mkdir" and potentially ignore real errors as well as (irrelevant)
> > EEXISTs.  I'm sure you're aware of all that, but your target audience
> > might not spot the implication if you don't make it explicit.
> 
> That's a good point and worth mentioning.  I'll make a note for a future 
> revision (currently trying to interest a publisher in a 'GNU Make 
> Cookbook' of all my articles 
> (http://www.cmcrossroads.com/content/category/8/147/268) on GNU Make stuff).

One other minor nit; the article implies that any change to any file in
a directory modifies the directory's timestamp.  That's not the case:
only changes that modify the directory entry table, such as adding a new
file, removing a file, or renaming a file (or subdirectory) will cause
the directory's timestamp to change.

That's one reason this issue is a bit tricky: sometimes it will work
fine but other times it will rebuild everything.

BTW, these semantics are true for POSIX systems; I'm not sure about
Windows.


Cheers!

-- 
-------------------------------------------------------------------------------
 Paul D. Smith <address@hidden>          Find some GNU make tips at:
 http://www.gnu.org                      http://make.paulandlesley.org
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist