This question may sound a little absurd. Facts:
I have a program written in C++.
It uses lot of in-house libs.
I don't have read permission to the libs.
So I have to build with a given tool which does have access to the lib headers and archives.
Stuck on gcc 4.3
I have a local build of gcc 4.5
I want g++ to use my local g++ instead of the old version.
Is there any way to get this done?
Use the full path of the compiler instead of invoking it without specifying the path.
Many configure scripts accept the CC environment variable:
export CC=/usr/bin/gcc44 for example. If you have a configure script, try ./configure --help to see if it's supported.
Assuming you have g++ in your ~/bin folder, could you add
export PATH=~/bin:$PATH
to your shell's .profile file (.bash_profile for bash). Then when you log in again and do which g++ it should show your local version of g++.
Related
So I got several shared libraries that I am trying to permanently install on my Ubuntu system but I am having some difficulty with it.
I want to install the libraries and the headers in a separate folder under /usr/local/lib and /usr/local/include (for example a folder named agony) so it would be clean and removing them would just require that I delete those folders. so it looks something like this:
/usr/local/lib/agony/libbtiGPIO.so
/usr/local/lib/agony/libbtiDSP.so
...
/usr/local/include/agony/GPIO.h
/usr/local/include/agony/DSP.h
...
And I added a file here /etc/ld.so.conf.d/agony.conf which include a line describing the path to the library folder:
$ cat /etc/ld.so.conf.d/agony.conf
/usr/local/lib/agony
and I perform sudo ldconfig to update the library database.
So to double check if the library is found I do ldconfig -p | grep bti* and
I see the following result:
$ ldconfig -p | grep bti
...
libbtiGPIO.so (libc6,x86-64) => /usr/local/lib/agony/libbtiGPIO.so
libbtiDSP.so (libc6,x86-64) => /usr/local/lib/agony/libbtiDSP.so
...
At this point I should be able to use the libraries without specifying the library path. But When I attempt to compile an application without providing the library path (-L) it fails. However, when I supply gcc with the library path ex:
gcc source.c -L /usr/local/lib/agony output -lbtiGPIO -lbtiDSP
it works!!
I don't want to use LD_LIBRARY_PATH environment variable because this library is going to be used everywhere on the system and I don't want other compilers to worry about providing LD_LIBRARY_PATH.
What am I doing wrong here?
At this point I should be able to use the libraries without specifying the library path
Here lies the confusion.
You have built your shared library libbtiGPIO.so (just sticking with that one),
placed it in /usr/local/lib/agony, and updated the ldconfig database accordingly.
The effect of that is when you run a program that has been linked with libbtiGPIO
then the dynamic linker (/lib/x86_64-linux-gnu/ld-2.21.so, or similar) will know where to look
to load that library into the process and you will not need to tell it by setting an LD_LIBRARY_PATH in the environment.
However, you haven't done anything that affects the list of default library
search directories that are hardwired into your build of gcc, that it passes to
the linker (/usr/bin/ld) when you link a program with libbtiGPIO in the first place.
That list of default search directories is what you will find if your do a verbose
build of your program - gcc -v ... - and then pick out the value of LIBRARY_PATH
from the output, e.g.
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/5/:\
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/:\
/usr/lib/gcc/x86_64-linux-gnu/5/../../../../lib/:\
/lib/x86_64-linux-gnu/:\
/lib/../lib/:\
/usr/lib/x86_64-linux-gnu/:\
/usr/lib/../lib/:\
/usr/lib/gcc/x86_64-linux-gnu/5/../../../:\
/lib/:\
/usr/lib
/usr/local/lib/agony is not one of those and to make it one of those you
would have to build gcc from source yourself. Hence, in order to link your
program with libbtiGPIO you still need to tell ld where to find it with
-L/usr/local/lib/agony -lbtiGPIO.
man, you misunderstand the procedure of complier and link.
First, libbtiGPIO.so is a shared link library not a static link library. it is important to know those difference .
Then you need to know something else. changing ld.so.conf.d/*.conf and run sudo ldconfig, it affects the procedure of link. in other words, if you don't add agony.conf and sudo ldconfig, you will receive a error when you run ./a.out rather than gcc source.c -L ...., the gcc command can run successfully even thougth you don't ldconfig.
Finally,if you don't pollute the LD_LIBRARY_PATH environment variable, you have to add -L ... options in your gcc command. What'more, if you don't want to input too many words in your shell frequently, you can learn to use Makefile.
I am trying to use libfann version 2.0.1 instead of the newest version 2.2.0, but could not figure out how to do so. Any thoughts on how to do that?
normally that works perfectly:
gcc fann_calculator.c -o run_fann_calculator -lfann -lm
where fann_calculator.c contains a program that calls a neural network.
Thanks
It depends upon where the two libraries sit. If they are installed in the same directory (e.g. both installed in /usr/lib/) you'll probably get the youngest one.
I suggest to carefully read the ld.so(8) and ldd(1) man pages. You certainly can trace what library is loaded (with e.g. the LD_DEBUG envirnonment variable). Don't forget to re-run ldconfig appropriately after library installation.
You could also play some LD_LIBRARY_PATH trick; for instance, set it to $HOME/lib:/usr/lib and install appropriate symlinks in your $HOME/lib/ to the precise library you want. For instance, you might do
ln -s /usr/lib/libfann.so.2.0.1 $HOME/lib/libfann.so.2
export LD_LIBRARY_PATH=$HOME/lib:/usr/lib:/lib
then check with ldd run_fann_calculator that you get the expected [version of the] libfann library.
Don't forget to read the Program Library Howto. You might want to pass appropriate flags to ld such as -rpath. You may need to pass them using gcc, perhaps with Gcc Link Options such as -Wl
I've a shell on a system without root privileges. I am trying to use a custom library for my new project and it cannot be installed onto the system because I don't have the root privilege. I'm building the library from source. Making the '.o' from the sources has been done. I've tried passing the '.o' file, generated after building the source, as the library argument (-l) to gcc , but gcc says file not found. Any possible workarounds for this?
Just pass the .o as an extra bit just like the rest of your program.
gcc <library.o> <yourprogram.o> -o <executable>
gcc -L/path/to/library/directory
LD_LIBRARY_PATH=/path/to/library/directory:$LD_LIBRARY_PATH ./a.out
My gcc compiler is at a custom location /my/path/hpgcc
I've downloaded the boost sources. Executed bootstrap.sh, but it fails because it runs with the default gcc.
Looking into it, I see that it fails at the first thing it does: building the Boost.Build engine:
gcc -o bootstrap/jam0 command.c compile.c debug.c expand.c glob.c hash.c hdrmacro.c headers.c jam.c jambase.c jamgram.c lists.c make.c make1.c newstr.c option.c output.c parse.c pathunix.c pathvms.c regexp.c rules.c scan.c search.c subst.c timestamp.c variable.c modules.c strings.c filesys.c builtins.c pwd.c class.c native.c md5.c w32_getreg.c modules/set.c modules/path.c modules/regex.c modules/property-set.c modules/sequence.c modules/order.c execunix.c fileunix.c
(fails because executed with the default gcc, and not my gcc version).
I've tried to change the gcc path in the user-config.jam file, but it doesn't help. Probably because the Boost.Build's build script boost_1_47_0/tools/build/v2/engine/build.sh doesn't use user-config.jam, and just uses the default locations.
Any solution?
Add the line:
using gcc : : /my/path/hpgcc ;
to user-config.jam. user-config.jam will usually be in /path/to/boost/tools/build/v2/, but you can put a custom user-config.jam or site-config.jam in any of the places listed here.
/my/path/hpgcc should be the full path to the g++ executable.
EDIT (Igor Oks) : What eventually solved the problem is that I edited boost_1_47_0/tools/build/v2/engine/build.sh to make it use my custom gcc.
We do this in our build environment by simply defining the PATH and LD_LIBRARY_PATH environment variables to pickup our desired GCC first.
I've got a proprietary program that I'm trying to use on a 64 bit system.
When I launch the setup it works ok, but after it tries to update itself and compile some modules and it fails to load them.
I'm suspecting it's because it's using gcc and gcc tries to compile them for a 64 bit system and therefore this program cannot use these modules.
Is there any way (some environmental variables or something like that) to force gcc to do everything for a 32 bit platform. Would a 32 bit chroot work?
You need to make GCC use the -m32 flag.
You could try writing a simple shell script to your $PATH and call it gcc (make sure you don't overwrite the original gcc, and make sure the new script comes earlier in $PATH, and that it uses the full path to GCC.
I think the code you need is just something like /bin/gcc -m32 $* depending on your shell (the $* is there to include all arguments, although it might be something else – very important!)
You may get a 32-bit binary by applying Alan Pearce's method, but you may also get errors as follows:
fatal error: bits/predefs.h: No such file or directory
If this is the case and if you have apt-get, just install gcc-multilib
sudo apt-get install gcc-multilib
For any code that you compile directly using gcc/g++, you will need to add -m32 option to the compilation command line, simply edit your CFLAGS, CXXFLAGS and LDFLAGS variables in your Makefile.
For any 3rd party code you might be using you must make sure when you build it to configure it for cross compilation. Run ./configure --help and see which option are available. In most cases you can provide your CFLAGS, CXXFLAGS and LDFLAGS variables to the configure script. You also might need to add --build and --host to the configure script so you end up with something like
./configure CFLAGS=-m32 CXXFLAGS=-m32 LDFLAGS=-m32 --build=x86_64-pc-linux-gnu --host=i686-pc-linux-gnu
If compilation fails this probably means that you need to install some 32 bit development packages on your 64 bit machine