%% "Andrew Ferguson" <[EMAIL PROTECTED]> writes:
af> I have a question that I was hoping someone could answer. I am
af> trying to understand which characters have special significance in
af> a rule command section and which participants are involved in
af> processing them.
af> target: dep1.ext dep2.ext dep3.ext
af> command --opt1 val1 etc..
af> how can you predicate which characters will be given special
af> significance? It seems the section of text after the rule header
af> is processed by make itself before being passed to the underlying
af> shell?
A command script is evaluated for make variables. So, "$" is special
and needs to be quoted (as "$$") if you want to pass a literal "$" to
the shell.
Then the command is passed to the shell, as if you had typed this:
$(SHELL) -c '...command...'
where SHELL is, unless reset in the makefile, "/bin/sh".
af> At the moment, I'm aware that the following may do some textual
af> processing before passing the commands on to the next layer
af> (1) Make
af> (2) A shell (or can tools sometimes be invoked direct by OS
af> process creation api?)
Make will sometimes invoke a command directly, for performance reasons,
but ONLY if it determines that the command is "simple enough" to be done
with a straightforward fork/exec, and not require any shell
capabilities.
af> (3) The tool itself
I guess I'm not sure what you're driving at. Make will evaluate for
make variables. Everything else should work exactly as if you'd typed
the command at the shell prompt.
--
-------------------------------------------------------------------------------
Paul D. Smith <[EMAIL PROTECTED]> 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
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