periodically check if a service is running

[rupert <rupertt gmail com>]

Hello,

imm trying to create a small window that shows me if a serice is running and
displays a small icon that shows the status
i created this function that checks if a PID is there:

gint check_samba(){
   gint smb_pid2;
   gchar check_smb_cmd[512];
   sprintf(check_smb_cmd, "cat /var/run/samba/smbd.pid 2>/dev/null");
   //g_print("%s", check_smb_cmd);
   smb_pid2 = system(check_smb_cmd);
   //g_print("%s", smb_pid2);
   return smb_pid2;
}

the function is called here:

 gint smb_pid;
 smb_pid=check_samba();
 //g_print("PID: %i", smb_pid);
//while(1){
     if(smb_pid > 0)
     {
         image1 =  g_object_new(GTK_TYPE_IMAGE,"file", "pics/ledgreen.png",
NULL);
     }else{
         image1 =  g_object_new(GTK_TYPE_IMAGE,"file", "pics/ledred.png",
NULL);
     }
 //}

 gtk_widget_show (image1);


So how can I check and if neccessary change the picture lets say every each
2 seconds?
I thought i could use an endless while loop, but that didnt worked.
Also the PID gets displayes when I call the function, but a g_print("PID:
%i", smb_pid); give me (null)
has been quite a while since i worked with C, so this may be a dump error by
me.

thx for your help