"loading shared libraries" error using VLFeat in C - c

Question

I am trying to use VLFeat library in C, as given on the website
http://www.vlfeat.org/gcc.html.
I downloaded and installed the library. I use the glnxa64 architecture. The library is located at /A/B/C/vlfeat-0.9.18
My code is as follows:
extern "C" {
#include <vl/generic.h>
#include <vl/sift.h>
}
int main (int argc, const char * argv[])
{
VL_PRINT ("Hello world!") ;
return 0;
}
I compile my code using the following statement,
g++ main.cpp -o vlfeat-test -I/A/B/C/vlfeat-0.9.18 -L/A/B/C/vlfeat-0.9.18/bin/glnxa64/ -lvl
But when I run it, I get the following error
./vlfeat-test: error while loading shared libraries: libvl.so: cannot open shared object file: No such file or directory

Answer 1

When your program is loaded, linux loads the necessary libraries.
You need to create a symbolic link in /usr/lib/ to your libvl.so file
sudo ln -s /home/[YourPATH]/vlfeat-0.9.20/bin/[YourArchitecture]/libvl.so /usr/lib/libvl.so

Answer 2

Before running your test, in the same console:
export LD_LIBRARY_PATH=/A/B/C/vlfeat-0.9.18/bin/glnxa64:$LD_LIBRARY_PATH
then
./vlfeat-test

Answer 3

I think the problem is when your program load. Linux doesn't know where your vl library is.
copy libvl.so to /usr/lib
sudo cp [VLFEAT_PATH]/bin/[YOUR_ARCHITECTURE]/libvl.so /usr/lib

Answer 4

[This worked for same problem when using the .mex files through MATLAB in Ubuntu].
You may need to update the links and cache to the recent shared libraries by running
sudo ldconfig
You can permanently add the library path /A/B/C/vlfeat-0.9.18/bin/glnxa64 or a custom directory with your (links to) shared libraries, e.g., /home/username/lib in the ldconfig files:
sudo vim /etc/ld.so.conf
to add the line(s)
/A/B/C/vlfeat-0.9.18/bin/glnxa64
Verify by running
ldconfig -v | grep libvl.so