Cross compiling for RPi - error while loading shared libraries

Question

I'm trying to compile a simple program on my Ubuntu using the ARM cross compile toolchain (arm-linux-gnueabihf-gcc) and run it on my Raspberry Pi. The program is using the wiringPi shared library (wiringPi.so) located in ~/wiringPi/wiringPi on Ubuntu. The code follows:

#include "wiringPi.h"

int main (void)
{
    wiringPiSetup();
    pinMode(0, OUTPUT);

    for (;;)
    {
        digitalWrite(0, HIGH);
        delay(500);
        digitalWrite(0, LOW);
        delay(500);
    }

    return 0;
}

I used the command:

arm-linux-gnueabihf-gcc blinking.c -o blinking -L ~/wiringPi/wiringPi -lwiringPi -I ~/wiringPi/wiringPi

to compile and successfully get the object file, which I then transfer to Raspberry Pi.
However, when trying to run the program on Pi, I get the following error:
./blinking: error while loading shared libraries: libwiringPi.so: cannot open shared object file: No such file or directory

What am I missing?

Answer 1

Shared or dynamic libraries are needed at run time. So you need the library not only on the build system but in on the target system, in this case on the PI.

This is different from static libraries. If you use a static library at build time, all the needed code from the library would be included in the executable, and the library would not be needed to run the program.

So you have to copy the library to the PI into a directory that is searched for shared libraries, such as /usr/lib or /usr/local/lib. You can also set LD_LIBRARY_PATH to point to the library, but then you must make sure it is always set when you want to execute the program.