FWIW here's a pattern I prefer. Start with this special target:
.SECONDEXPANSION:
Once this is in place, the pattern is that every single rule gets a
standard order-only dependency called $$(@D):
foo/bar: blah blah ... | $$(@D)
This evaluates to the containing directory of the target which means it
must always exist when needed (assuming a separate rule to make
directories):
dirA dirB dirC ...:
mkdir -p $@
The main value here is that $$(@D) is completely boilerplate and could be
supplied by a macro or your AI or whatever. Even if it evaluates to ".",
which will often be the case, no harm done. The extra $ is needed due to
the secondary expansion.
David
On Thu, Apr 30, 2026 at 3:27 PM Heime <[email protected]> wrote:
> On Friday, May 1st, 2026 at 6:59 AM, Tim Murphy <[email protected]>
> wrote:
>
> > Hi,
> >
> > I did have a reason, which wasn't tied up with GNU make. Trying to
> explain wont help you but there is a other way.
> >
> > One problem with directories is that their time and date change when
> anything is done on the directory e.g. if a new file is created. I think
> you might need to check that adding a file to one of your directories
> doesn't trigger mıdır on anything below it. Does this matter a lot? Not
> really in this case.
>
> You recommond a variation to this:
>
> ${infdir}: $(docdir)
> ${hmldir}: ${docdir}
> ${docdir} ${infdir} ${hmldir}:
> mkdir -p $@
>
> > In my unusual situation it causes a very bad performance regression so I
> had to use another scheme.
> >
> > What was effective for me was a variable that one appended the directory
> to and then at the end of the makefile a for loop that ran something like
> $(eval $$(shell mkdır -p ... ) on batches of about 20 directories at a time.
>
> Right. Followed by the rules to make your targets after making the
> directories
> present in the variable.
>
> > If you're not making 100s of directories you don't need to be too
> sophisticated.
>
> I will only have a few directories. Nothing more.
>
> > Best regards,
> >
> > Tim Murphy
> >
> >
> > On Thu, 30 Apr 2026, 19:29 Heime, <[email protected]> wrote:
> >
> > >
> > > I made the following makefile, where .info and html files are
> > > stored in docs/info and docs/html directories. Whilst single
> > > file antares.pdf and antares.dvi are stored in directory docs.
> > >
> > > Have included order-only prerequisite for directories with the
> > > rules defined as shown. Would one rather do something different
> > > for making the directories if they don't exist?
> > >
> > > docdir = ${HOME}/Opfeld/hist/build/${btnver}/docs
> > > infdir = ${HOME}/Opfeld/hist/build/${btnver}/docs/info
> > > hmldir = ${HOME}/Opfeld/hist/build/${btnver}/docs/html
> > >
> > > srcs = ${srcdir}/antares.texi
> > >
> > > opts = --force --enable-encoding -I ${srcdir}
> > >
> > > $(infdir)/antares.info: $(srcs) | $(infdir)
> > > makeinfo $(opts) -o $@ $<
> > >
> > > $(hmldir)/antares.html: $(srcs) | $(hmldir)
> > > makeinfo $(opts) --html -o $@ $<
> > >
> > > $(docdir)/antares.pdf: $(srcs) | $(docdir)
> > > makeinfo $(opts) --pdf -o $@ $<
> > >
> > > $(docdir)/antares.dvi: $(srcs) | $(docdir)
> > > makeinfo $(opts) --dvi -o $@ $<
> > >
> > > ${infdir}: $(docdir)
> > > ${hmldir}: ${docdir}
> > > ${docdir} ${infdir} ${hmldir}:
> > > mkdir -p $@
>
>
>
