linux before main example

linux_before_main/build.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+# Path setup
+src=$PWD
+cd ..
+mkdir -p build
+cd build
+
+
+# Build
+gcc -fvisibility=hidden $src/linux_before_main.c -o linux_before_main
+

linux_before_main/linux_before_main.c

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+// define the "before main" function
+int x = 0;
+__attribute__((constructor))
+static void run_before_main_func(void){
+  x = 100;
+}
+
+
+// main
+#include <stdio.h>
+int main(){
+  printf("x = %d\n", x);
+  return(0);
+}