OpenGL v Linuxe

/usr/lib/gcc/i486-linux-gnu/4.3.2/../../../../lib/crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: ld returned 1 exit status

#include <GL/glut.h>    // Header File For The GLUT Library
#include <GL/gl.h>   // Header File For The OpenGL32 Library
#include <GL/glu.h>   // Header File For The GLu32 Library
#include <unistd.h>     // Header file for sleeping.

/* ascii code for the escape key */
#define ESCAPE 27

/* The number of our GLUT window */
int window;

/* A general OpenGL initialization function.  Sets all of the initial parameters. */
void InitGL(int Width, int Height)           // We call this right after our OpenGL window is created.
{
  glClearColor(0.0f, 0.0f, 0.0f, 0.0f);      // This Will Clear The Background Color To Black
  glClearDepth(1.0);            // Enables Clearing Of The Depth Buffer
  glDepthFunc(GL_LESS);            // The Type Of Depth Test To Do
  glEnable(GL_DEPTH_TEST);         // Enables Depth Testing
  glShadeModel(GL_SMOOTH);         // Enables Smooth Color Shading

  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();            // Reset The Projection Matrix

  gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);   // Calculate The Aspect Ratio Of The Window

  glMatrixMode(GL_MODELVIEW);
}

/* The function called when our window is resized (which shouldn't happen, because we're fullscreen) */
void ReSizeGLScene(int Width, int Height)
{
  if (Height==0)            // Prevent A Divide By Zero If The Window Is Too Small
    Height=1;

  glViewport(0, 0, Width, Height);      // Reset The Current Viewport And Perspective Transformation

  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);
  glMatrixMode(GL_MODELVIEW);
}

/* The main drawing function. */
void DrawGLScene()
{
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);      // Clear The Screen And The Depth Buffer
  glLoadIdentity();            // Reset The View

  // since this is double buffered, swap the buffers to display what just got drawn.
  glutSwapBuffers();
}

/* The function called whenever a key is pressed. */
void keyPressed(unsigned char key, int x, int y)
{
    /* avoid thrashing this procedure */
    usleep(100);

    /* If escape is pressed, kill everything. */
    if (key == ESCAPE)
    {
   /* shut down our window */
   glutDestroyWindow(window);
   
   /* exit the program...normal termination. */
   exit(0);                   
    }
}

int main(int argc, char **argv)
{ 
  /* Initialize GLUT state - glut will take any command line arguments that pertain to it or
     X Windows - look at its documentation at http://reality.sgi.com/mjk/spec3/spec3.html */ 
  glutInit(&argc, argv); 

  /* Select type of Display mode:   
     Double buffer
     RGBA color
     Alpha components supported
     Depth buffer */ 
  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_ALPHA | GLUT_DEPTH); 

  /* get a 640 x 480 window */
  glutInitWindowSize(640, 480); 

  /* the window starts at the upper left corner of the screen */
  glutInitWindowPosition(0, 0); 

  /* Open a window */ 
  window = glutCreateWindow("Jeff Molofee's GL Code Tutorial ... NeHe '99"); 

  /* Register the function to do all our OpenGL drawing. */
  glutDisplayFunc(&DrawGLScene); 

  /* Go fullscreen.  This is as soon as possible. */
  glutFullScreen();

  /* Even if there are no events, redraw our gl scene. */
  glutIdleFunc(&DrawGLScene);

  /* Register the function called when our window is resized. */
  glutReshapeFunc(&ReSizeGLScene);

  /* Register the function called when the keyboard is pressed. */
  glutKeyboardFunc(&keyPressed);

  /* Initialize our window. */
  InitGL(640, 480);
 
  /* Start Event Processing Engine */ 
  glutMainLoop(); 

  return 1;
}

lesson1.c:(.text+0x2a): undefined reference to `glClearColor'
lesson1.c:(.text+0x34): undefined reference to `glClearDepth'
lesson1.c:(.text+0x40): undefined reference to `glDepthFunc'
lesson1.c:(.text+0x4c): undefined reference to `glEnable'
lesson1.c:(.text+0x58): undefined reference to `glShadeModel'
lesson1.c:(.text+0x64): undefined reference to `glMatrixMode'
lesson1.c:(.text+0x69): undefined reference to `glLoadIdentity'
lesson1.c:(.text+0x97): undefined reference to `gluPerspective'
lesson1.c:(.text+0xa3): undefined reference to `glMatrixMode'
/tmp/cclWUuAc.o: In function `ReSizeGLScene':
lesson1.c:(.text+0xda): undefined reference to `glViewport'
lesson1.c:(.text+0xe6): undefined reference to `glMatrixMode'
lesson1.c:(.text+0xeb): undefined reference to `glLoadIdentity'
lesson1.c:(.text+0x119): undefined reference to `gluPerspective'
lesson1.c:(.text+0x125): undefined reference to `glMatrixMode'
/tmp/cclWUuAc.o: In function `DrawGLScene':
lesson1.c:(.text+0x139): undefined reference to `glClear'
lesson1.c:(.text+0x13e): undefined reference to `glLoadIdentity'
lesson1.c:(.text+0x143): undefined reference to `glutSwapBuffers'
/tmp/cclWUuAc.o: In function `keyPressed':
lesson1.c:(.text+0x170): undefined reference to `glutDestroyWindow'
/tmp/cclWUuAc.o: In function `main':
lesson1.c:(.text+0x19e): undefined reference to `glutInit'
lesson1.c:(.text+0x1aa): undefined reference to `glutInitDisplayMode'
lesson1.c:(.text+0x1be): undefined reference to `glutInitWindowSize'
lesson1.c:(.text+0x1d2): undefined reference to `glutInitWindowPosition'
lesson1.c:(.text+0x1de): undefined reference to `glutCreateWindow'
lesson1.c:(.text+0x1f0): undefined reference to `glutDisplayFunc'
lesson1.c:(.text+0x1f5): undefined reference to `glutFullScreen'
lesson1.c:(.text+0x202): undefined reference to `glutIdleFunc'
lesson1.c:(.text+0x20e): undefined reference to `glutReshapeFunc'
lesson1.c:(.text+0x21a): undefined reference to `glutKeyboardFunc'
lesson1.c:(.text+0x233): undefined reference to `glutMainLoop'
collect2: ld returned 1 exit status

gcc -Wall -O2 -lGL -lGLU -L/usr/X11R6/lib -lglut main.c -o gl-test

/usr/bin/ld: cannot find -lglut
collect2: ld returned 1 exit status