The Linux Development Platform Configuring, Using, and ... - Classes

CH03.fm Page 55 Monday, October 7, 2002 8:33 PM
Installing GNU Compiler 55
GCC_EXEC_PREFIX
COMPILER_PATH
LIBRARY_PATH
C_INCLUDE_PATH
OBJC_INCLUDE_PATH
CPLUS_INCLUDE_PAT
H
LD_LIBRARY_PATH
If this variable is set, GCC will look into the directory to find sub
programs.
This is a colon-separated list of directories that GCC uses to find
out sub programs if search fails using GCC_EXEC_PREFIX variable.
This is a colon-separated list of directories that is used to find out
libraries for linking process.
Colon separated list of directories to find out header files for C
programs.
Colon separated list of directories to find out header files for
Objective C programs.
Colon separated list of directories to find out header files for C++
programs.
Path for shared libraries.
There are other environment variables and settings that GCC uses while building a target.
You can display these using the –v command line switch with the gcc command when you
compile a program. This will show you the path including files, programs used during the compilation
process, and command line arguments and switches passed to each of these programs.
The following is the output of the command when you compile the hello.c program.
[rr@conformix 4]$ gcc -v hello.c
Reading specs from /opt/gcc-3.0.4/lib/gcc-lib/i686-pc-linuxgnu/3.0.4/specs
Configured with: ../gcc-3.0.4/configure --prefix=/opt/gcc-
3.0.4 --enable-threads=posix
Thread model: posix
gcc version 3.0.4
/opt/gcc-3.0.4/lib/gcc-lib/i686-pc-linux-gnu/3.0.4/cc1 -langc
-v -D__GNUC__=3 -D__GNUC_MINOR__=0 -D__GNUC_PATCHLEVEL__=4 -
D__ELF__ -Dunix -Dlinux -D__ELF__ -D__unix__ -D__linux__ -
D__unix -D__linux -Asystem=posix -D__NO_INLINE__ -
D__STDC_HOSTED__=1 -Acpu=i386 -Amachine=i386 -Di386 -D__i386 -
D__i386__ -D__tune_i686__ -D__tune_pentiumpro__ hello.c -quiet
-dumpbase hello.c -version -o /tmp/ccJsUmYa.s
GNU CPP version 3.0.4 (cpplib) (i386 Linux/ELF)
GNU C version 3.0.4 (i686-pc-linux-gnu)
compiled by GNU C version 3.0.4.
ignoring nonexistent directory "/opt/gcc-3.0.4/i686-pc-linuxgnu/include"
#include "..." search starts here:
#include search starts here:
/usr/local/include