Script mostrado en https://www.lastdragon.net/?p=2260

o.sh

#!/bin/env bash
# https://www.lastdragon.net/?p=2260

cat > programa.c << EOF
#include <stdio.h>

double powern(double d, unsigned n)
{
  double x = 1.0;
  unsigned j;

  for (j = 1; j <= n; j++)
    x *= d;

  return x;
}

int main(void)
{
  double sum = 0.0;
  unsigned i;

  for (i = 1; i <= 1000000000; i++)
  {
    sum += powern (i, i % 5);
  }

  printf ("sum = %g\n", sum);
  return 0;
}
EOF

echo "Compilando y ejecutando sin optimizacion"
gcc -Wall -O0 programa.c -lm -o programa
ls -l programa
time ./programa
rm -f programa
echo ""

echo "Compilando y Optimizando nivel 1"
gcc -Wall -O1 programa.c -lm -o programa
ls -l programa
time ./programa
rm -f programa
echo ""