Intel XENIX 286 Programmers Guide (86) - Tenox.tc

make: Program Maintainer XENIX Programming
The MAKE macro provides a way to override the -n option and execute selected
commands in a makefile. When MAKE is used in a command, make will always execute
that command, even if -n has been given in the invocation. The variable may be set to
any value or command sequence.
The MAKEFLAGS macro contains one or more make options and can be used in
invocations of make from within a makefile. You may assign any make options to
MAKEFLAGS except -f, -p, and -d. If you do not assign a value to the macro, make
automatically assigns the current options to it, i.e., the options given in the current
invocation.
The MAKE and MAKEFLAGS macros, together with the -n option, are typically used to
debug makefiles that generate entire software systems. For example, in the following
makefile, setting MAKE to "make" and invoking this file with the -n option displays all
the commands used to generate the programs progl, prog2, and prog3 without actually
executing them.
system : prog 1 prog2 prog3
@echo System complete.
prog 1 : prog 1.c
$(MAKE) $(MAKE FLAGS) prog 1
prog2 : prog2.c
$(MAKE) $(MAKEFLAGS) prog2
prog3 : prog3.c
$(MAKE) $(MAKEFLAGS) prog3
Using the Built-In Rules
make provides a set of built-in dependency lines, called built-in rules, that
automatically check the targets and dependents given in a makefile and create up-todate
versions of these files if necessary. The built-in rules are identical to user-defined
dependency lines except that they use the suffix of the file name as the target or
dependent instead of the file name itself. For example, make automatically assumes
that all files with the suffix .o have dependent files with the suffixes .c and .s.
When no explicit dependency line is given in a makefile for a given file, make
automatically checks the default dependents of the file, forming the name of the
dependents by removing the suffix of the given file and appending the predefined
dependent suffixes. If the given file is out of date with respect to these default
dependents, make searches for a built-in rule that defines how to create an up to date
version of the file and executes it. There are built-in rules for the following files:
.o Object file
.c C source file
.r Ratfor source file
.f Fortran source file
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