Environment Variables - Red Hat ENTERPRISE LINUX 3 - USING CPP Using Instructions

This section describes the environment variables that affect how CPP operates. You can use them to
specify directories or prefixes to use when searching for include files, or to control dependency output.
Note that you can also specify places to search using options such as
output with options like
variables, which in turn take precedence over the configuration of GCC.
CPATH
C_INCLUDE_PATH
CPLUS_INCLUDE_PATH
OBJC_INCLUDE_PATH
Each variable's value is a list of directories separated by a special character, much like
which to look for header files. The special character,
determined at GCC build time. For Windows-based targets it is a semicolon, and for almost all
other targets it is a colon.
specifies a list of directories to be searched as if specified with
CPATH
given with
-I
which language is being preprocessed.
The remaining environment variables apply only when preprocessing the particular language
indicated. Each specifies a list of directories to be searched as if specified with
after any paths given with
See also Section 2.3 Search Path.
DEPENDENCIES_OUTPUT
If this variable is set, its value specifies how to output dependencies for Make based on the non-
system header files processed by the compiler. System header files are ignored in the dependency
output.
The value of
DEPENDENCIES_OUTPUT
written to that file, guessing the target name from the source file name. Or the value can have the
form
file target
name.
In other words, this environment variable is equivalent to combining the options
(Refer to Chapter 12 Invocation), with an optional
SUNPRO_DEPENDENCIES
This variable is the same as the environment variable
tem header files are not ignored, so it implies
the main input file is omitted. Refer to Chapter 12 Invocation.
(Refer to Chapter 12 Invocation). These take precedence over environment
-M
options on the command line. The environment variable is used regardless of
-isystem
, in which case the rules are written to file

Environment Variables

PATH_SEPARATOR
options on the command line.
can be just a file name, in which case the Make rules are
switch too.
-MT
DEPENDENCIES_OUTPUT
rather than
-M
Chapter 13.
, and control dependency
-I
, is target-dependent and
, but after any paths
-I
-isystem
using
file target
, except that sys-
. However, the dependence on
-MM
, in
PATH
, but
as the target
and
-MM -MF