Re: GNU Make problem with $(shell ... )

[Paul D. Smith]

%% address@hidden writes:

  tm> Now it gets a little more complicated because the contents of
  tm> INFO_FILE get modified during the build, and I only want to
  tm> evaluate FOO after INFO_FILE has been modified However what I'm
  tm> finding is that if I modify the contents of INFO_FILE and then
  tm> evaluate FOO in the same rule, then FOO uses the *old* contents of
  tm> INFO_FILE and not the updated contents. If I move the operations
  tm> into different rules then FOO contains the correct information
  tm> (although obviously I have to ensure that the rules get evaluted
  tm> in the correct order)

All the variables and functions in a rule script are evaluated before
the first line is run.  For example, in:

  foo:
        echo $(FOO)
        echo $(BAR)

Make goes:

  evaluate FOO, evaluate BAR, run echo $(FOO), run echo $(BAR)

and NOT:

  evaluate FOO, run echo $(FOO), evaluate BAR, run echo $(BAR)

  tm> Any ideas?

It's not clear to me what you're _really_ trying to do.  Note that make
is _NOT_ a procedural language; most of the time it doesn't just walk
from the top of the file to the bottom and invoke commands.

Further, note that you cannot set a make variable from within a command
script; those scripts are invoked in sub-shells and as with all
processes in UNIX, a child process cannot modify the environment of its
parent.

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