boost and cpp-netlib make compile ERROR

Question

[SOLVED] created symlinks from /usr/lib/lib/* to /usr/lib*

[UPDATE 3] NEW VERSION:

Ok, I think I fixed something

use find / -name "libboost_system.*" outout was

/usr/include/boost/lib/libboost_system.so
/usr/include/boost/lib/libboost_system.a
/usr/include/boost/lib/libboost_system.so.1.46.1
/usr/lib/lib/libboost_system.so
/usr/lib/lib/libboost_system.a
/usr/lib/lib/libboost_system.so.1.46.1
/usr/local/include/boost_1_46_1/bin.v2/libs/system/build/gcc-4.4.3/release/link-static/threading-multi/libboost_system.a
/usr/local/include/boost_1_46_1/bin.v2/libs/system/build/gcc-4.4.3/release/threading-multi/libboost_system.so.1.46.1
/usr/local/lib/libboost_system.so
/usr/local/lib/libboost_system.a
/usr/local/lib/libboost_system.so.1.46.1
/root/tmp/boost_1_46_1/bin.v2/libs/system/build/gcc-4.4.3/release/link-static/threading-multi/libboost_system.a
/root/tmp/boost_1_46_1/bin.v2/libs/system/build/gcc-4.4.3/release/threading-multi/libboost_system.so.1.46.1

why are these files in /usr/lib/lib ? and is it a problem ?

and the ls -l /usr/lib/lib | grep boost_system

ls -l /usr/lib/lib | grep boost_system
-rw-r--r-- 1 root root   21574 2011-05-09 15:15 libboost_system.a
lrwxrwxrwx 1 root root      25 2011-05-09 15:15 libboost_system.so -> libboost_system.so.1.46.1
-rwxr-xr-x 1 root root   20053 2011-05-09 15:15 libboost_system.so.1.46.1

atm my makefile looks like

LIBPATH=-I/usr/local/include/cpp-netlib 
LIBS=$(LIBPATH) -lboost_system  -lboost_filesystem -lboost_thread -lpthread 

LD=g++ -g 
CPP=g++ -c -g $(LIBS)

P=.
OBJ=$(P)/tmp/main.o $(P)/tmp/CLink.o $(P)/tmp/CFetcher.o

main:   $(OBJ); $(LD) $(OBJ) $(LIBS) -o $@


$(P)/tmp/CLink.o:   $(P)/src/CLink.cpp $(P)/include/CLink.h; $(CPP) -c $< -o $@
$(P)/tmp/CFetcher.o:    $(P)/src/CFetcher.cpp $(P)/include/CFetcher.h; $(CPP) -c $< -o $@
$(P)/tmp/main.o:    $(P)/src/main.cpp $(P)/include/CLink.h $(P)/include/CFetcher.h ; $(CPP) -c $< -o $@

all:
    touch $(P)/tmp/*.o;
    touch main;
    rm -f $(P)/tmp/*.o;
    rm -f main;
    make main;

The Compiler output is lie

g++ -c -g -I/usr/local/include/cpp-netlib  -lboost_system  -lboost_filesystem -lboost_thread -lpthread  -c src/main.cpp -o tmp/main.o
g++ -c -g -I/usr/local/include/cpp-netlib  -lboost_system  -lboost_filesystem -lboost_thread -lpthread  -c src/CLink.cpp -o tmp/CLink.o
g++ -c -g -I/usr/local/include/cpp-netlib  -lboost_system  -lboost_filesystem -lboost_thread -lpthread  -c src/CFetcher.cpp -o tmp/CFetcher.o
g++ -g  ./tmp/main.o ./tmp/CLink.o ./tmp/CFetcher.o -I/usr/local/include/cpp-netlib  -lboost_system  -lboost_filesystem -lboost_thread -lpthread  -o main

So for me all looks nice but when i try to run the program

./main

./main: error while loading shared libraries: libboost_system.so.1.46.1: cannot open shared object file: No such file or directory

Answer 1

1. The -l flags must come after the source files on linker command-line.

   Yes, that means you'll have to split the LD definition to LD and LIBS, put all the -L and -l flags in the later and change the link command to:

   $(LD) $(OBJ) $(LIBS) -o $@

2. The library (.so (dynamic) or .a (static)) files have to be the same version as the headers. While there are boost 1.46.1 headers installed in /usr/local/include/boost_1_46_1/, the corresponding library files don't seem to be installed at all. The only installed libraries are version 1.40.0 in /usr/lib, so the linker finds those (/usr/lib would be searched by default even if you didn't include the -L/usr/lib flag), but they don't contain the symbols expected by 1.46.1.

   Note that when linking against shared library (using shared libraries is strongly recommended in Linux), the linker looks for the file with .so extension, but that is usually symlink to a file with added version suffix and the linker reads it and records the target name in the binary. That way programs compiled against the .1.40 will continue to work when 1.46 is installed, because the libboost*.so.1.40.0 may (and have to) stay around after the .so is redirected to the 1.46.1 version.

   It should be even possible to install like:

   /usr/local/lib/boost_1_46_1/libboost_system-mt.so -> /usr/local/lib/libboost_system-mt.so.1.46
   /usr/local/lib/libboost_system-mt.so.1.46 -> /usr/local/lib/libboost_system-mt.so.1.46.1
   /usr/local/lib/libboost_system-mt.so.1.46.1
   

   and compile using -L/usr/local/lib/boost_1_46_1, though I currently can't find any package that would do it to confirm this. This way you could have development files for multiple versions installed and switch between them using explicit -I and -L flags while dynamic linker would still find the runtime files, for which it only looks in /usr/local/lib, /usr/lib and /lib (it can be configured in /etc/ld.so.conf, but that's the default).

Answer 2

Execute your application with strace. This will show the location were you app is looking for your boost libs. In my case an app was looking in /usr/lib/x86_64-linux-gnu for boost libs where the actual location was /usr/lib/lib. A simple export statement adding the paths for the boost shared libs in my case LD_LIBRARY_PATH=/usr/lib/lib worked a treat.

output from strace

open("/usr/lib/x86_64-linux-gnu/libboost_system.so.1.46.1", O_RDONLY) = -1 ENOENT (No such file or directory)
exit_group(127)                         = ?