Reverse engineering GCC output - need library file (name) and path.
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I am posting this here because I hope the actual output will help to solve the issue , and it is not small! I have an app using bluetooth - linked to library "bluetooth". It works fine. I need to identify the actual type of library ( Linux .a or .so ). GCC options do not require prefix, such as "lib." or suffix - .a or .so thus GCC output cannot tell me the library file full name. I also need the (-L) path to the library and GCC does not correlate -L with -l. Help will be appreciated. PS Please ignore the "undefined.." error. Here is the actual GCC linker output
make all
Building target: RPI_BT_SERVER
Invoking: GCC C++ Linker
g++ -L/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_COMMON/src/MODULES/M_SOCKET_COMMON -L"/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_LIB/Debug" -v -o "RPI_BT_SERVER" ./src/MODULES/M_FILE_CLASS/CFILECLASS.o ./src/RPI_BT_SERVER.o -lbluetooth -lRPI_BT_LIB
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.12' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.12)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64- -
I am posting this here because I hope the actual output will help to solve the issue , and it is not small! I have an app using bluetooth - linked to library "bluetooth". It works fine. I need to identify the actual type of library ( Linux .a or .so ). GCC options do not require prefix, such as "lib." or suffix - .a or .so thus GCC output cannot tell me the library file full name. I also need the (-L) path to the library and GCC does not correlate -L with -l. Help will be appreciated. PS Please ignore the "undefined.." error. Here is the actual GCC linker output
make all
Building target: RPI_BT_SERVER
Invoking: GCC C++ Linker
g++ -L/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_COMMON/src/MODULES/M_SOCKET_COMMON -L"/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_LIB/Debug" -v -o "RPI_BT_SERVER" ./src/MODULES/M_FILE_CLASS/CFILECLASS.o ./src/RPI_BT_SERVER.o -lbluetooth -lRPI_BT_LIB
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.12' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.12)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-Knowing "why" helps to motivate people; otherwise, it sounds like "make work". Seems like knowing what OS you're running under would be more useful.
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it. ― Confucian Analects: Rules of Confucius about his food
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I am posting this here because I hope the actual output will help to solve the issue , and it is not small! I have an app using bluetooth - linked to library "bluetooth". It works fine. I need to identify the actual type of library ( Linux .a or .so ). GCC options do not require prefix, such as "lib." or suffix - .a or .so thus GCC output cannot tell me the library file full name. I also need the (-L) path to the library and GCC does not correlate -L with -l. Help will be appreciated. PS Please ignore the "undefined.." error. Here is the actual GCC linker output
make all
Building target: RPI_BT_SERVER
Invoking: GCC C++ Linker
g++ -L/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_COMMON/src/MODULES/M_SOCKET_COMMON -L"/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_LIB/Debug" -v -o "RPI_BT_SERVER" ./src/MODULES/M_FILE_CLASS/CFILECLASS.o ./src/RPI_BT_SERVER.o -lbluetooth -lRPI_BT_LIB
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.12' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.12)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64- -
I am posting this here because I hope the actual output will help to solve the issue , and it is not small! I have an app using bluetooth - linked to library "bluetooth". It works fine. I need to identify the actual type of library ( Linux .a or .so ). GCC options do not require prefix, such as "lib." or suffix - .a or .so thus GCC output cannot tell me the library file full name. I also need the (-L) path to the library and GCC does not correlate -L with -l. Help will be appreciated. PS Please ignore the "undefined.." error. Here is the actual GCC linker output
make all
Building target: RPI_BT_SERVER
Invoking: GCC C++ Linker
g++ -L/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_COMMON/src/MODULES/M_SOCKET_COMMON -L"/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_LIB/Debug" -v -o "RPI_BT_SERVER" ./src/MODULES/M_FILE_CLASS/CFILECLASS.o ./src/RPI_BT_SERVER.o -lbluetooth -lRPI_BT_LIB
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.12' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.12)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-try
ldd _myprog_. If the library shows up in the output, then it is dynamically linked, e.g. a.solibrary. If it doesn't, then its a static library (.a). Usually the linker (ld, not gcc), will prefer the dynamic library over the static, so the resulting executable will a) use new versions of the library, if it gets updated, and b) (less important these days) have a smaller on-disk footprint. If you are linking to the .so and you want to force the linker to use the static library you can do that with the following options to gcc-Wl,-Bstatic -l_some_lib_ -Wl,-Bdynamic
If you don't add the
-Wl,-Bdynamicat the end, then libc gets statically linked in, too, which is probably not what you want. Of course you could just pass-staticto gcc for the final linking stage, and that will produced a static binary (no shared libs), which should run on most linux boxes of with the same architecture (e.g X86 or ARM). I say most, because if you compiled on say Ubuntu 18.04, and tried to run on something ancient, like maybe RedHat 9 (shrike), you would probably get a execution error. But it would be helpful to know why you want to know this. Normally, we don't care whether we're linking to a dynamic or static library, just as long as the program works. Your question suggests to me that you're bumping up against an issue and are trying to force the OS into doing what you think it should, rather than working with the OS -
try
ldd _myprog_. If the library shows up in the output, then it is dynamically linked, e.g. a.solibrary. If it doesn't, then its a static library (.a). Usually the linker (ld, not gcc), will prefer the dynamic library over the static, so the resulting executable will a) use new versions of the library, if it gets updated, and b) (less important these days) have a smaller on-disk footprint. If you are linking to the .so and you want to force the linker to use the static library you can do that with the following options to gcc-Wl,-Bstatic -l_some_lib_ -Wl,-Bdynamic
If you don't add the
-Wl,-Bdynamicat the end, then libc gets statically linked in, too, which is probably not what you want. Of course you could just pass-staticto gcc for the final linking stage, and that will produced a static binary (no shared libs), which should run on most linux boxes of with the same architecture (e.g X86 or ARM). I say most, because if you compiled on say Ubuntu 18.04, and tried to run on something ancient, like maybe RedHat 9 (shrike), you would probably get a execution error. But it would be helpful to know why you want to know this. Normally, we don't care whether we're linking to a dynamic or static library, just as long as the program works. Your question suggests to me that you're bumping up against an issue and are trying to force the OS into doing what you think it should, rather than working with the OS -
I am posting this here because I hope the actual output will help to solve the issue , and it is not small! I have an app using bluetooth - linked to library "bluetooth". It works fine. I need to identify the actual type of library ( Linux .a or .so ). GCC options do not require prefix, such as "lib." or suffix - .a or .so thus GCC output cannot tell me the library file full name. I also need the (-L) path to the library and GCC does not correlate -L with -l. Help will be appreciated. PS Please ignore the "undefined.." error. Here is the actual GCC linker output
make all
Building target: RPI_BT_SERVER
Invoking: GCC C++ Linker
g++ -L/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_COMMON/src/MODULES/M_SOCKET_COMMON -L"/media/z/DEV_COPY_LABEL/ECLIPSE_FOLDER/2019-12/Eclipse_2019_12/eclipse/Workspace_2019_12/RPI_BT_LIB/Debug" -v -o "RPI_BT_SERVER" ./src/MODULES/M_FILE_CLASS/CFILECLASS.o ./src/RPI_BT_SERVER.o -lbluetooth -lRPI_BT_LIB
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.12' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.12)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-pick it in the makefile
ifeq (,$(wildcard somelibpath/sonelibrary.a))
// The library is .a
endififeq (,$(wildcard somelibpath/sonelibrary.so))
// The library is .so
endifYou can even pick it out of a list of filenames in the makefile .. that is after all what the makefile is there for
In vino veritas
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Knowing "why" helps to motivate people; otherwise, it sounds like "make work". Seems like knowing what OS you're running under would be more useful.
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it. ― Confucian Analects: Rules of Confucius about his food
-
pick it in the makefile
ifeq (,$(wildcard somelibpath/sonelibrary.a))
// The library is .a
endififeq (,$(wildcard somelibpath/sonelibrary.so))
// The library is .so
endifYou can even pick it out of a list of filenames in the makefile .. that is after all what the makefile is there for
In vino veritas