test_objects.sh

#!/bin/bash

set -x

# Create three source files: test1.c, test2.c, test3.c
cat <<EOT > test1.c
int func1();
int func2();
int func3();

int func1() {
  return 1;
}
EOT

cat <<EOT > test2.c
int func1();
int func2();
int func3();

int func2() {
  return 2 + func1();
}
EOT

cat <<EOT > test3.c
int func1();
int func2();
int func3();

int func3() {
  return 3 + func2();
}
EOT

# Compile them
gcc -c test1.c -o test1.o
gcc -c test2.c -o test2.o
gcc -c test3.c -o test3.o

# Link a relocatable object, get 1 .o file instead of 3 different ones
gcc -r -nostdlib test1.o test2.o test3.o -o reloc.o

# A small test program
cat <<EOT > main.c
#include <stdio.h>

int func3();

int main() {
  printf("%d\n", func3());  // should print 6
  return 0;
}
EOT

# Compile and link it with relocatable object
gcc main.c reloc.o -o main

# Run app
./main