multiple targets in a rule

[sharan basappa]

This looks very simple .. somehow I cant figure it out ..

   Gnu make manual speficies that a rule of type :
   bigoutput littleoutput : text.g
   generate text.g -$(subst output,,$@) > $@
   is same as :
   bigoutput : text.g
   generate text.g -big > bigoutput
   littleoutput : text.g
   generate text.g -little > littleoutput

   I have a simple make with one rule that says :
   a.o b.o : a.c
   When I execute this make all I get is
   Reading makefiles...
   Reading makefile `Make10'...
   Updating goal targets....
   Considering target file `a.o'.
   File `a.o' does not exist.
     Considering target file `a.c'.
      Finished prerequisites of target file `a.c'.
     No need to remake target `a.c'.
     Pruning file `a.c'.
   Finished prerequisites of target file `a.o'.
   Must remake target `a.o'.
   cc    -c -o a.o a.c
   Successfully remade target file `a.o'.

   Is there a reason why target b.o is considered by make ?

   Regards,
   Sharan

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