How can I type "cargo run" without needing to set the LD_LIBRARY_PATH shell variable?

Question

I build a Rust program that calls a C++ function via a C interface. In order to execute the program, I have to run:

export LD_LIBRARY_PATH=<path to shared c lib>

or I get an error:

error while loading shared libraries: libtest.so: cannot open shared object file: No such file or directory

I tried to set the variable in a build script using std::process::Command

Command::new("sh").arg("export").arg("LD_LIBRARY_PATH=<path to shared c lib>");

Although the command executes without an error, the variable is not set. How can I set the variable from my program while it is being executed?

To be more concrete, I want to type only this:

cargo run

instead of

export LD_LIBRARY_PATH=<path to shared c lib>
cargo run

My code so far:

main.rs

/*---compile all with---
    g++ -c -fpic foo.cpp
    gcc -c -fpic test.c
    g++ -shared foo.o test.o -o libtest.so

    in order to execute we have to set the variable
    export LD_LIBRARY_PATH=/home/jan/Uni/Bachelorarbeit/Programme/Rust_Cpp_crossover_erneut/$LD_LIBARY_PATH

*/
//pub extern crate c_interface;
pub extern crate libc;
use libc::{c_int};



#[link(name = "test")]
extern "C" {
    fn hello_world () -> c_int;
}


fn main() {
    let x;
    unsafe {
        x = hello_world();
    }
    println!("x is: {}", x);
}

test.c

#include "foo.h"

int hello_world () {
    int a = foo();
    return a;
}

foo.cpp

#include <iostream>
#include "foo.h"

using namespace std;

int foo() {
    cout << "Hello, World!" << endl;
    return 0;
}

foo.h

#ifdef __cplusplus
extern "C" {
#endif

int foo();

#ifdef __cplusplus
}
#endif

build.rs

fn main () {
    println!(r"cargo:rustc-link-search=native=/home/jan/Uni/Bachelorarbeit/Programme/Rust_Cpp_crossover_erneut");
}

I have seen How do I specify the linker path in Rust? and it is not a solution to my problem.

Answer 1

Add the following line to build.rs:

println!("cargo:rustc-env=LD_LIBRARY_PATH=/home/jan/Uni/Bachelorarbeit/Programme/Rust_Cpp_crossover_erneut/");

This only works with cargo run and not with cargo build and then executing the output. The environment variable does not get saved into the binary.