I have some code that uses some shared libraries (c code on gcc). When compiling I have to explicitly define the include and library directories using -I and -L, since they aren't in the standard places. When I try to run the code, I get the following error:
./sync_test
./sync_test: error while loading shared libraries: libsync.so: cannot open shared object file: No such file or directory
However, do the following, everything works just fine:
export LD_LIBRARY_PATH="/path/to/library/"
./sync_test
Now, the strange part is, this only works once. If I try and run sync_test again I get the same error unless I run the export command first. I tried adding the following to my .bashrc, but it made no difference:
LD_LIBRARY_PATH="/path/to/library/"
This question is related to
c
linux
gcc
shared-libraries
ld
Use
export LD_LIBRARY_PATH="/path/to/library/"
in your .bashrc otherwise, it'll only be available to bash and not any programs you start.
Try -R/path/to/library/ flag when you're linking, it'll make the program look in that directory and you won't need to set any environment variables.
EDIT: Looks like -R is Solaris only, and you're on Linux.
An alternate way would be to add the path to /etc/ld.so.conf and run ldconfig. Note that this is a global change that will apply to all dynamically linked binaries.
What you also can do, if it's something you installed on your system, is to add the directory that contains the shared libraries to your /etc/ld.so.conf file, or make a new file in /etc/ld.so.conf.d/
(I've both checked RHEL5 and Ubuntu distribution so I think it's generic for linux)
The ldconfig program will make sure they are system-wide included.
See the following link for more information: www.dwheeler.com/secure-programs/Secure-Programs-HOWTO/dlls.html
You can just put this all on one line:
LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/path/to/library" ./sync_test
Should make things a little easier, even if it doesn't change anything fundamental
You could add in your code a call system with the new definition:
sprintf(newdef,"export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:%s:%s",ld1,ld2);
system(newdef);
But, I don't know it that is the rigth solution but it works.
Regards
You should avoid setting LD_LIBRARY_PATH in your .bashrc. See "Why LD_LIBRARY_PATH is bad" for more information.
Use the linker option -rpath while linking so that the dynamic linker knows where to find libsync.so during runtime.
gcc ... -Wl,-rpath /path/to/library -L/path/to/library -lsync -o sync_test
Another way would be to use a wrapper like this
#!/bin/bash
LD_LIBRARY_PATH=/path/to/library sync_test "$@"
If sync_test starts any other programs, they might end up using the libs in /path/to/library which may or may not be intended.
Instead of overriding the library search path at runtime with LD_LIBRARY_PATH, you could instead bake it into the binary itself with rpath. If you link with GCC adding -Wl,-rpath,<libdir> should do the trick, if you link with ld it's just -rpath <libdir>.
Did you 'export' in your .bashrc?
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:"/path/to/library"
Source: Stackoverflow.com