1@c Copyright (c) 1999, 2000, 2001, 2002, 2004 2@c Free Software Foundation, Inc. 3@c This is part of the CPP and GCC manuals. 4@c For copying conditions, see the file gcc.texi. 5 6@c --------------------------------------------------------------------- 7@c Environment variables affecting the preprocessor 8@c --------------------------------------------------------------------- 9 10@c If this file is included with the flag ``cppmanual'' set, it is 11@c formatted for inclusion in the CPP manual; otherwise the main GCC manual. 12 13@vtable @env 14@item CPATH 15@itemx C_INCLUDE_PATH 16@itemx CPLUS_INCLUDE_PATH 17@itemx OBJC_INCLUDE_PATH 18@c Commented out until ObjC++ is part of GCC: 19@c @itemx OBJCPLUS_INCLUDE_PATH 20Each variable's value is a list of directories separated by a special 21character, much like @env{PATH}, in which to look for header files. 22The special character, @code{PATH_SEPARATOR}, is target-dependent and 23determined at GCC build time. For Microsoft Windows-based targets it is a 24semicolon, and for almost all other targets it is a colon. 25 26@env{CPATH} specifies a list of directories to be searched as if 27specified with @option{-I}, but after any paths given with @option{-I} 28options on the command line. This environment variable is used 29regardless of which language is being preprocessed. 30 31The remaining environment variables apply only when preprocessing the 32particular language indicated. Each specifies a list of directories 33to be searched as if specified with @option{-isystem}, but after any 34paths given with @option{-isystem} options on the command line. 35 36In all these variables, an empty element instructs the compiler to 37search its current working directory. Empty elements can appear at the 38beginning or end of a path. For instance, if the value of 39@env{CPATH} is @code{:/special/include}, that has the same 40effect as @samp{@w{-I. -I/special/include}}. 41 42@c man end 43@ifset cppmanual 44See also @ref{Search Path}. 45@end ifset 46@c man begin ENVIRONMENT 47 48@item DEPENDENCIES_OUTPUT 49@cindex dependencies for make as output 50If this variable is set, its value specifies how to output 51dependencies for Make based on the non-system header files processed 52by the compiler. System header files are ignored in the dependency 53output. 54 55The value of @env{DEPENDENCIES_OUTPUT} can be just a file name, in 56which case the Make rules are written to that file, guessing the target 57name from the source file name. Or the value can have the form 58@samp{@var{file} @var{target}}, in which case the rules are written to 59file @var{file} using @var{target} as the target name. 60 61In other words, this environment variable is equivalent to combining 62the options @option{-MM} and @option{-MF} 63@ifset cppmanual 64(@pxref{Invocation}), 65@end ifset 66@ifclear cppmanual 67(@pxref{Preprocessor Options}), 68@end ifclear 69with an optional @option{-MT} switch too. 70 71@item SUNPRO_DEPENDENCIES 72@cindex dependencies for make as output 73This variable is the same as @env{DEPENDENCIES_OUTPUT} (see above), 74except that system header files are not ignored, so it implies 75@option{-M} rather than @option{-MM}. However, the dependence on the 76main input file is omitted. 77@ifset cppmanual 78@xref{Invocation}. 79@end ifset 80@ifclear cppmanual 81@xref{Preprocessor Options}. 82@end ifclear 83@end vtable 84