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7.5 Variables used when building a program

Occasionally it is useful to know which Makefile variables Automake uses for compilations; for instance you might need to do your own compilation in some special cases.

Some variables are inherited from Autoconf; these are CC, CFLAGS, CPPFLAGS, DEFS, LDFLAGS, and LIBS.

There are some additional variables which Automake itself defines:

INCLUDES ¶

A list of ‘-I’ options. This can be set in your Makefile.am if you have special directories you want to look in. Automake already provides some ‘-I’ options automatically. In particular it generates ‘-I$(srcdir)’ and a ‘-I’ pointing to the directory holding config.h (if you’ve used AC_CONFIG_HEADER or AM_CONFIG_HEADER).

INCLUDES can actually be used for other cpp options besides ‘-I’. For instance, it is sometimes used to pass arbitrary ‘-D’ options to the compiler.

COMPILE ¶

This is the command used to actually compile a C source file. The filename is appended to form the complete command line.

LINK ¶

This is the command used to actually link a C program.