I'm having trouble getting a sample program to link correctly (in this case against the ICU library). When I do 'make', everything builds fine. But when I run it, it says it can't find one of the .so's. I double checked they're all installed in /usr/local/lib. What I discovered was it was looking in /usr/lib. If I symlink from there to there actual location, it works.
Why is my LIBPATHS being ignored or not used?
Here is the Makefile
CC = g++
INCPATHS = -I/usr/local/include
CFLAGS = -c -Wall $(INCPATHS)
LIBPATHS = -L/usr/local/lib/
LIBS = $(LIBPATHS) -licuio -licui18n -licuuc -licuio -licudata
EXECUTABLE = prog
print_linking = echo -e "\033[32m" "Linking: $<" "\033[39m"
print_compiling = echo -e "\033[33m" "Compiling: $<" "\033[39m"
print_cleaning = echo -e "\033[31m" "Cleaning: `pwd`" "\033[39m"
all: main
# [target]: [dependencies]
# <tab> system command
main: main.o
#$(print_linking)
#$(CC) -o $(EXECUTABLE) main.o $(LIBS) >> /dev/null
main.o: main.cpp
#$(print_compiling)
#$(CC) $(CFLAGS) main.cpp
clean:
#$(print_cleaning)
#rm -rf *.o *~ $(EXECUTABLE)
Your LIBPATHS tells the linker where to find the library when linking to resolve symbols.
At runtime, you need to tell the loader where to find the library. It doesn't know about what happened at compile time. You can use the LD_LIBRARY_PATH variable as mentioned above, or check into /etc/ld.so.conf and it's friends.
The path to the dynamic libraries isn't stored in the executable by default. You can either:
use LD_LIBRARY_PATH at runtime to give a path where to search for dynamic libraries
use -Wl,-Rpath at link time to store a path in the executable
One solution is to add /usr/local/lib to the environment variable LD_LIBRARY_PATH.
You can do this in your .profile or .cshrc
You can also get the linker to store the full path to the library in the executable.
Both solutions have different tradeoffs with respect to using the execultable by different users and/or on different machines.
Related
I'm currently developing a C++ application which will reference multiple *.so libraries, each containing code for different machines - written in C.
I also have one shared object containing code from a custom namespace Utilities, which (as the name implies) contains basic utilities useful for the application (written in C++, like the rest of the application).
Currently, utilities.so is the only (custom) library referenced by the application.
The application compiles and links just fine, however executing it on the target hardware display the following error: bin/updater_v4test: error while loading shared libraries: ../../../bin/device_modules/utilities.so.1.0.0: cannot open shared object file: No such file or directory
When calling LDD on said application, the following output is shown: ../../../bin/device_modules/utilities.so.1.0.0 => not found
I've written a script which (upon make exiting without errors) collects all SOs and pushes them in to the /lib/ directory on the target hardware; meaning that upon each successful build of the application (whether in part or entirely), the updated files are pushed to the correct directory on the target hardware.
In an attempt to mimic other libraries I've used (e.g. zlib), I've attempted to create a symlink to the library file, with no luck (utilities.so.1.0.0 is the symlink, utilities.so is the actual SO).
utilities.so.1.0.0 --> utilities.so
At the moment I'm at a loss, and I can't waste much more time in trying to figure this out myself.
Below is an excerpt from the utilities Makefile:
include ../../common/user.mk
LIB_DIR=../../../libs/lib/powerpc-linux-gnu
CFLAGS=-Wall -ggdb -I../../libs/include -I../../common -lpthread -lddc -std=c++0x -I../../libs/include/zlib
LDFLAGS=../../libs/lib/powerpc-linux-gnu/libcurl.so.4 ../../libs/include/minizip/.libs/libminizip.so.1.0.0 \
-L ../../libs/lib \
-L ../../libs/lib/powerpc-linux-gnu \
-Wl,-rpath-link,../../libs/lib/powerpc-linux-gnu \
-lrt -lddc -lpthread -shared
BIN_DIR=../bin
CANONICAL_BIN_DIR := $(shell readlink -f $(BIN_DIR))
CANONICAL_CUR_DIR := $(shell readlink -f "./")
COMP_OBJECTS := $(wildcard *.cpp)
OBJECTS := $(patsubst %.cpp,%.o,$(wildcard *.cpp))
all: objects utilities.so
-cp --parents utilities.so $(GLOBAL_BIN_LIB)
-ln -s utilities.so utilities.so.1.0.0
-mv utilities.so.1.0.0 $(GLOBAL_BIN_LIB)
# -cp --parents *.h $(GLOBAL_HEADER_DIR)
-rm -f utilities.so
-rm -f *.o
for header in $(wildcard *.h); do \
echo $$header; \
ln -s $(CANONICAL_CUR_DIR)/$$header $(GLOBAL_HEADER_DIR)/$$header; \
done;
#printf "########## BUILT $^ ##########\n\n"
utilities.so: $(OBJECTS)
${CXX} $^ -o $# ${LDFLAGS}
objects: $(COMP_OBJECTS)
${CXX} -c $^ ${CFLAGS}
And now an excerpt from the application Makefile.
Here I've added a reference to the library in the linker flags, the header files are all included in from one directory.
include ../../../common/user.mk
LIB_DIR=../../../libs/lib/powerpc-linux-gnu
CFLAGS=-Wall -ggdb -I../../../libs/include -I${COMMON_DIR} -lpthread -lddc -std=c++0x -I../../../libs/include/zlib -I${HEADER_DIR}
LDFLAGS=../../../libs/lib/powerpc-linux-gnu/libcurl.so.4 ../../../libs/include/minizip/.libs/libminizip.so.1.0.0 ../../../bin/device_modules/utilities.so.1.0.0 \
-L ../../../libs/lib \
-L ../../../libs/lib/powerpc-linux-gnu \
-Wl,-rpath-link,../../../libs/lib/powerpc-linux-gnu \
-lrt -lddc -lpthread -L ${SO_DIR}
BIN_DIR=../bin
CANONICAL_BIN_DIR := $(shell readlink -f $(BIN_DIR))
CANONICAL_CUR_DIR := $(shell readlink -f "./")
all: test_update.bin
-cp --parents test_update.bin $(BIN_DIR)
-ln -s $(CANONICAL_BIN_DIR)/test_update.bin $(GLOBAL_BIN_APP)/test_update.bin
-rm -f *.bin
#printf "########## BUILT $^ ##########\n\n"
test_update.bin: main.o updaterdelegate.o commonfunctions.o tinyxml.o
${CXX} $^ -o $# ${LDFLAGS}
####################
# Required Files #
####################
main.o: Main.cpp
${CXX} -c $^ -o $# ${CFLAGS}
updaterdelegate.o: UpdaterDelegate.cpp
${CXX} -c $^ -o $# ${CFLAGS}
commonfunctions.o: $(shell python -c "import os.path; print os.path.relpath('${IMPL_CMN_FUNC}'.replace('\"', ''), '${CANONICAL_CUR_DIR}'.replace('\"', ''))")
${CXX} -c $^ -o $# ${CFLAGS}
tinyxml.o: $(shell python -c "import os.path; print os.path.relpath('${IMPL_TXML}'.replace('\"', ''), '${CANONICAL_CUR_DIR}'.replace('\"', ''))")
${CXX} -c $^ -o $# ${CFLAGS}
####################
# /Required Files #
####################
Just for gits and shiggles, I'll add the build output of the utilities.so and application.
utilities.so:
(Clean ommitted)
=============== CLEAN COMPLETE... BUILDING... ===============
make: Entering directory `~/_workspace/upv4/common/utils'
powerpc-linux-gnu-g++ -c ArgumentHandling.cpp Extensions.cpp Logging.cpp -Wall -ggdb -I../../libs/include -I../../common -lpthread -lddc -std=c++0x -I../../libs/include/zlib
ArgumentHandling.cpp: In member function ‘void Utilities::ArgumentHandler::freeMemory()’:
ArgumentHandling.cpp:136: warning: deleting ‘void*’ is undefined
powerpc-linux-gnu-g++ ArgumentHandling.o Extensions.o Logging.o -o utilities.so ../../libs/lib/powerpc-linux-gnu/libcurl.so.4 ../../libs/include/minizip/.libs/libminizip.so.1.0.0 -L ../../libs/lib -L ../../libs/lib/powerpc-linux-gnu -Wl,-rpath-link,../../libs/lib/powerpc-linux-gnu -lrt -lddc -lpthread -shared
cp --parents utilities.so """~/_workspace/upv4""/bin/device_modules"
ln -s utilities.so utilities.so.1.0.0
mv utilities.so.1.0.0 """~/_workspace/upv4""/bin/device_modules"
rm -f utilities.so
rm -f *.o
for header in ArgumentHandling.h Enumerations.h Extensions.h Logging.h; do \
echo $header; \
ln -s ~/_workspace/upv4/common/utils/$header """"~/_workspace/upv4""/bin/device_modules"/headers"/$header; \
done;
ArgumentHandling.h
Enumerations.h
Extensions.h
Logging.h
########## BUILT objects utilities.so ##########
make: Leaving directory `~/_workspace/upv4/common/utils'
=============== BUILD COMPLETE... PARSING... ===============
========== Warnings ==========
Total: 1
ArgumentHandling.cpp:136: warning: deleting ‘void*’ is undefined
========== Errors ==========
Total: 0
test_update.bin:
(Clean ommitted)
=============== CLEAN COMPLETE... BUILDING... ===============
make: Entering directory `~/_workspace/_workspace/upv4/test/app/src'
powerpc-linux-gnu-g++ -c Main.cpp -o main.o -Wall -ggdb -I../../../libs/include -I"""~/_workspace/_workspace/upv4""/common" -lpthread -lddc -std=c++0x -I../../../libs/include/zlib -I"""""~/_workspace/_workspace/upv4""/bin/device_modules"/headers""
powerpc-linux-gnu-g++ -c UpdaterDelegate.cpp -o updaterdelegate.o -Wall -ggdb -I../../../libs/include -I"""~/_workspace/_workspace/upv4""/common" -lpthread -lddc -std=c++0x -I../../../libs/include/zlib -I"""""~/_workspace/_workspace/upv4""/bin/device_modules"/headers""
powerpc-linux-gnu-g++ -c ../../../common/commonFunctions.cpp -o commonfunctions.o -Wall -ggdb -I../../../libs/include -I"""~/_workspace/_workspace/upv4""/common" -lpthread -lddc -std=c++0x -I../../../libs/include/zlib -I"""""~/_workspace/_workspace/upv4""/bin/device_modules"/headers""
powerpc-linux-gnu-g++ -c ../../../common/xmlreader/tinyxml2.cpp -o tinyxml.o -Wall -ggdb -I../../../libs/include -I"""~/_workspace/_workspace/upv4""/common" -lpthread -lddc -std=c++0x -I../../../libs/include/zlib -I"""""~/_workspace/_workspace/upv4""/bin/device_modules"/headers""
powerpc-linux-gnu-g++ main.o updaterdelegate.o commonfunctions.o tinyxml.o -o test_update.bin ../../../libs/lib/powerpc-linux-gnu/libcurl.so.4 ../../../libs/include/minizip/.libs/libminizip.so.1.0.0 ../../../bin/device_modules/utilities.so.1.0.0 -L ../../../libs/lib -L ../../../libs/lib/powerpc-linux-gnu -Wl,-rpath-link,../../../libs/lib/powerpc-linux-gnu -lrt -lddc -lpthread -L """"~/_workspace/_workspace/upv4""/bin/device_modules""
cp --parents test_update.bin ../bin
ln -s ~/_workspace/_workspace/upv4/test/app/bin/test_update.bin """~/_workspace/_workspace/upv4""/bin"/test_update.bin
ln: failed to create symbolic link `~/_workspace/_workspace/upv4/bin/test_update.bin': File exists
make: [all] Error 1 (ignored)
rm -f *.bin
########## BUILT test_update.bin ##########
make: Leaving directory `~/_workspace/_workspace/upv4/test/app/src'
=============== BUILD COMPLETE... PARSING... ===============
========== Warnings ==========
Total: 0
========== Errors ==========
Total: 0
The build script is custom, I built it myself to rid myself of the entire make output when I don't need it, and it parses out all the errors and warnings.
Due to the issue, I have turned make output back on.
Did I miss something during compilation/linking of the library, or is something going wrong during the linking of the application?
I'm inclined to say it's during compilation/linking of the library - although I don't know what exactly is going wrong, as everything is compiling and linking just fine.
Why is the application looking for the .so file in a path it can't possibly have?
I also made sure that the .so files are found with the $PATH variable, so the application should be able to find them.
The system normally searches for shared objects in a fixed set of directories. You can handle around this by defining the environment variable LD_LIBRARY_PATH and adding the directory where you install the shared libraries into.
Or you can add those libraries to some of the standard libraries directories and execute ldconfig -a to update the cache of shared libraries.
See ldconfig(8), for more info.
edit
There are two mechanisms to load a shared object.
The first is the normal library loading mechanism, that specifies what has to be loaded at start executable time, and implies linking your executable with the shared objects. This is what you do in your Makefile. You specify the shared executables, and the ld.so.xxx shared object (which is linked to your application when you are dynamically linking it) loads and follows all the unresolved identifiers to find a place for them in the virtual address space. The ld.so.xxx object uses the /etc/ld.so.cache file, that is just a hash table with the directories and shared executables available to be loaded this way. That file is indexed by what is called the soname (which is something useful to allow different versions of the same library to coexist in the same system) and normally maps to the last versioned shared found in the list of directories listed in the file /etc/ld.so.conf (this is static information to accelerate the process of loading libraries and is generated at each boot of the system). If the shared was found at link time (this mechanism is not used by ld, but only to load the libraries at program start time) to have a soname, then that soname is searched in the /etc/ld.so.cache to find the final file that has to be loaded. This cache is built on each boot of the system, so you don't have to cope with that, but only if you don't want to reboot and you install a new library for system use. It is important to note that shared objects must be given sonames for this to work, and that the list of directories in the file /etc/ld.so.conf are the only directories used to search for files. This means that for a standard library to be usable, you need to put it in one of this directories (or add the directory to the list in /etc/ld.so.conf) and then execute ldconfig -a to rebuild the cache and let it include a reference for the file under that soname.
The other way it to add to the list of search places a list in the form of a PATH variable. The variable is LD_LIBRARY_PATH so, in case you have your shared objects in ${HOME}/libs, you can add this line to your .profile:
export LD_LIBRARY_PATH=${HOME}/libs
or
setenv LD_LIBRARY_PATH ${HOME}/libs
this allows your library to live outside of the standard directories, but think twice, as this is a far less efficient way to load a file (as it involves processing a list of directories to look for the final shared objects, while the previous approach is direct, you ask for the file matching the soname that ld.so.xxx asks for, only one search, only one step)
The second is to use a library function dlopen(3) that allow you to load a shared object and do some housekeeping before calling anything inside. The dl library allows you to search for a symbol in the shared executable and then decide if you interpret it as data or a jump target. dlopen() just opens and loads into the virtual address space a shared object. It resolves the dependencies (if requested to) and is the more flexible way (but it is also nontransparent) to load unknown code for execution. This is the way plugins normally work. You decide in a config file, or dynamically what to load, and then you load it. The program doesn't have to know previously the symbol table of what you are dealing with and you are free to implement whatever you want in the module you are loading.
All of these methods work with ELF binaries, so you have a lot of freedom, but also a lot of complexity on it.
more...
As i've seen from your compilation:
you are including -l in the compile only commands, the libraries are only needed if you are linking an executable, don't put libraries in the compile phase.
for a library to be searched and selected by the linker, it has to be named as lib<name>.so (without the version info at the end) so this means that you normally find three names for a standard library (let me use the math library -lm as an example):
/usr/lib/libm.so.3.2.8 # this is the ELF file with the library contents.
/usr/lib/libm.so.3 -> libm.so.3.2.8 # this is the soname used to create the library.
/usr/lib/libm.so -> libm.so.3 # this is the actual file the ld(1) program searches for when using -lm.
those links have to be created, as the system normally doesn't. This is part of the installation procedure for a shared library. The soname link allows you to have different versions of a library and detect which one of them will be used at runtime (all must be compatible so you can interchange, when you make an incompatible modification, then you have to change the soname, so the system doesn't get confused on loading)
It is very important to know that the ld(1) program only selects a library if it is called lib<name>.so, with no version info. Indeed, the compiler first searchs for lib<name>.so, then for lib<name>.a, then it complains.
It is very important to put -L places to search for libraries before any -l option that will use those directories in the linking parameters.
You only need to run ldconfig -a and install the library in a system directory if you are not going to use the LD_LIBRARY_PATH mechanism. (this mechanism doesn't work for root account, for obvious reasons :))
Expecting this added comments give some light to the process.
I am attempting to install twitcurl on OS X and have met with some problems.
At first, running make would return the clang error: ld: unknown option: -soname. I looked through the responses from other users with similar problems on OS X and found the following advice:
In the makefile, change:
LDFLAGS += -Wl,-rpath-link=$(STAGING_DIR)/usr/lib
to:
LDFLAGS += -rpath=$(STAGING_DIR)/usr/lib
change:
$(CC) -shared -Wl,-soname,lib$(LIBNAME).so.1 $(LDFLAGS) -o lib$(LIBNAME).so.1.0 .o -L$(LIBRARY_DIR) -lcurl
to:
$(CC) -dynamiclib -shared -Wl,-install_name,lib$(LIBNAME).dylib.1 $(LDFLAGS) -o lib$(LIBNAME).dylib .o -L$(LIBRARY_DIR) -lcurl
I tried this, but the only result was another clang error: clang: error: unknown argument: '-rpath=/usr/lib'
Any advice towards installing twitcurl on an OS X system will be greatly appreciated.
----UPDATE----
I just wanted to put in one place all the steps I took to make this work, in case any OS X users with similar problems come across this in the future. My thanks to Andy Piper for the crucial pieces.
open the makefile and replace:
LDFLAGS += -Wl,-rpath-link=$(STAGING_DIR)/usr/lib
with:
LDFLAGS += -rpath $(STAGING_DIR)/usr/lib
and:
$(CC) -shared -Wl,-soname,lib$(LIBNAME).so.1 $(LDFLAGS) -o lib$(LIBNAME).so.1.0 .o -L$(LIBRARY_DIR) -lcurl
with:
$(CC) -dynamiclib -shared -Wl,-install_name,lib$(LIBNAME).dylib.1 $(LDFLAGS) -o lib$(LIBNAME).dylib *.o -L$(LIBRARY_DIR) -lcurl
(note that this is different by two characters from the advice another OS X user gave above)
after running make, copy libtwitcurl.dylib into /usr/lib/
Downloading the twitterClient (which is also the only code example I could find) will be the same, but for compiling it or your own programs you will need to link -lcurl as well. (g++ appname.cpp -ltwitcurl -lcurl)
Finally, once you compile a program, the path name will likely be incorrect in the executable which is created. Use install_name_tool to correct it. For me this looks like:
install_name_tool -change libtwitcurl.dylib.1 /usr/lib/libtwitcurl.dylib nameofexecutable
but if that doesn't work for you, use otool to find the actual path:
otool -L nameofexecutable
and then the first argument after -change should be the erroneous path for libtwitcurl. You can use otool again after running install_name_tool to be sure the change was successful.
I can get the shared / dynamic library to compile but needed to make a couple of adjustments to your Makefile:
LDFLAGS += -rpath $(STAGING_DIR)/usr/lib
and
$(CC) -dynamiclib -shared -Wl,-install_name,lib$(LIBNAME).dylib.1 $(LDFLAGS) -o lib$(LIBNAME).dylib *.o -L$(LIBRARY_DIR) -lcurl
I've now also built the associated twitterClient utility. To do so, I had to symbolically link libtwitcurl.dylib as libtwitcurl.dylib.1 and also change the consumer key and secret in the code to match a valid one from apps.twitter.com on my account. Works fine.
I assume you want to use the twitcurl library from code? Twitter maintains a Ruby-based utility, twurl, which has a similar function and may also be useful.
Well, after 3 hours of researching, I'm about to go insane, so I figure it's time to pass it off to some new eyes.
CXXFLAGS = -g -Wall
OBJS = main.o
PROG = test
INCLUDES = -I /usr/include/mysql -I /usr/local/include
LIBS = -L /usr/lib/mysql -l libmysqlclient.so.15.0.0 -L /usr/local/lib -l libmysqlpp.so.3.1.0
all: $(PROG)
${PROG}: $(OBJS)
$(CXX) $(INCLUDES) -o $(PROG) $(OBJS) $(LIBS)
clean:; $(RM) -f $(PROG) core *.o
There's something wrong with the include paths, because I get errors that mysql_version.h does not exist when it clearly does exist in /usr/include/mysql.
Checking the first part out of the ouput, it says
g++ -g -Wall -c -o main.o main.cpp
which makes me think that I've formatted something in the Makefile wrong (due to the extra spaces and lack of include/library paths). However, I've looked at dozens of manuals and articles on Makefiles and the g++ options and... no progress.
I assume this should be a simple fix. Please, please help (do you sense my despair?).
On another note, do you think specifying the library specifically is necessary? I had this stuff running in XCode just fine, but I'm trying to migrate the code to my web server... the Makefile has stopped all progress, and I figure it's something I should learn from.
In your makefile, you have added your include directives to the linking stage, not the compiling stage.
The lines
${PROG}: $(OBJS)
$(CXX) $(INCLUDES) -o $(PROG) $(OBJS) $(LIBS)
Say to make the program in ${PROG} from object files in ${OBJS} by calling the compiler in ${CXX} passing the include folders (along with your other arguments). Instead, for your variable section, do this:
INCLUDES = -I /usr/include/mysql -I /usr/local/include
CXXFLAGS = -g -Wall ${INCLUDES}
OBJS = main.o
PROG = test
LIBS = -L /usr/lib/mysql -l libmysqlclient.so.15.0.0 -L /usr/local/lib -l libmysqlpp.so.3.1.0
This way your CXXFLAGS (which are used for the compile stage) should now pickup your include directives.
I'm trying to create a shared library on ubuntu using gcc
I just have one simple class(shared.h and shared.cpp) and one client to use it (main.cpp)
This is my makefile and I'm still not able to to get the program to compile.
all:
#compile object(fPIC: creates position independent code)
gcc -fPIC -Wall -g -c shared.cpp
#compile shared library
gcc -shared -Wl,-soname,libshared.so.1 -o libshared.so.1.0.1 shared.o -lc
#link shared library
gcc -g -o main main.cpp -L. -lshared
I'm confident the first line is correct
I am unsure what "-lc" does. I think it passes something to the linker?
I don't want to install the library, I just want to be able to link it from the current directory. I have tried: export LD_LIBRARY_PATH=.
but it does not seem to make a difference. Everything is in the current directory.
ERROR: /usr/bin/ld: cannot find -lshared
how do I get the compiler to check the current directory for my library?
The problem is not that it's not looking in the directory, the problem is that you've named the library "libshared.so.1.0.1". When you use -lshared, it's looking for a file named 'libshared.so' or 'libshared.a' in the library search path.
Most of the time, when using versioned system libraries, you'll provide a link to the latest one as 'libshared.so', even if you have installed 'libshared.so.1' or 'libshared.so.1.0.1'.
In your case, if you continue to leave the file named 'libshared.so.1.0.1', you'll want to create 2 symbolic links:
libshared.so - So that the library can be found using ld
libshared.so.1 - Since you declared the SO name as libshared.so.1 when building it, you need to provide this link, otherwise, the executable will not be able to find the proper shared library at runtime.
You don't write any dependencies, which is the purpose of Makefile-s. And you probably need to force the run path Perhaps something like
.PHONY: all clean
CXX=g++
CXXFLAGS=-g -Wall
all: main
main: main.o libshared.so
$(LINK.cpp) -o $# $< -Wl,-rpath,. -L. -lshared
libshared.so: shared.pic.o
$(LINK.cpp) -shared -o $^ $<
main.o: main.cc shared.hh
%.pic.o: %.cc
$(CXX) $(CXXFLAGS) -fPIC -c -o $# $<
#
clean:
rm -f *.o *.so main *~
[SOLVED] created symlinks from /usr/lib/lib/* to /usr/lib*
[UPDATE 3] NEW VERSION:
Ok, I think I fixed something
use find / -name "libboost_system.*"
outout was
/usr/include/boost/lib/libboost_system.so
/usr/include/boost/lib/libboost_system.a
/usr/include/boost/lib/libboost_system.so.1.46.1
/usr/lib/lib/libboost_system.so
/usr/lib/lib/libboost_system.a
/usr/lib/lib/libboost_system.so.1.46.1
/usr/local/include/boost_1_46_1/bin.v2/libs/system/build/gcc-4.4.3/release/link-static/threading-multi/libboost_system.a
/usr/local/include/boost_1_46_1/bin.v2/libs/system/build/gcc-4.4.3/release/threading-multi/libboost_system.so.1.46.1
/usr/local/lib/libboost_system.so
/usr/local/lib/libboost_system.a
/usr/local/lib/libboost_system.so.1.46.1
/root/tmp/boost_1_46_1/bin.v2/libs/system/build/gcc-4.4.3/release/link-static/threading-multi/libboost_system.a
/root/tmp/boost_1_46_1/bin.v2/libs/system/build/gcc-4.4.3/release/threading-multi/libboost_system.so.1.46.1
why are these files in /usr/lib/lib ? and is it a problem ?
and the ls -l /usr/lib/lib | grep boost_system
ls -l /usr/lib/lib | grep boost_system
-rw-r--r-- 1 root root 21574 2011-05-09 15:15 libboost_system.a
lrwxrwxrwx 1 root root 25 2011-05-09 15:15 libboost_system.so -> libboost_system.so.1.46.1
-rwxr-xr-x 1 root root 20053 2011-05-09 15:15 libboost_system.so.1.46.1
atm my makefile looks like
LIBPATH=-I/usr/local/include/cpp-netlib
LIBS=$(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
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 $#
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).
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) = ?