ignore_action -- A build check method that ignores changes in the command.
ignore_action method is exactly like the
exact_match method except that it will not cause a rebuild if the command string changes. This method is intended to be used (along with the variable $(changed_inputs)) for commands that update an output file rather than remake it from scratch. For example,
libxyz.a : *.o : build_check ignore_action ar ru $(output) $(changed_inputs)
is one way that you can update an archive. (There are a number of reasons why updating an archive can lead to incorrect builds, however. See the makepp cookbook for details.)