FCHMOD: системные вызовы.

#include 
#define S_IRWXU 0000700    /* RWX mask for owner */
#define S_IRUSR 0000400    /* R for owner */
#define S_IWUSR 0000200    /* W for owner */
#define S_IXUSR 0000100    /* X for owner */
#define S_IRWXG 0000070    /* RWX mask for group */
#define S_IRGRP 0000040    /* R for group */
#define S_IWGRP 0000020    /* W for group */
#define S_IXGRP 0000010    /* X for group */
#define S_IRWXO 0000007    /* RWX mask for other */
#define S_IROTH 0000004    /* R for other */
#define S_IWOTH 0000002    /* W for other */
#define S_IXOTH 0000001    /* X for other */
#define S_ISUID 0004000    /* set user id on execution */
#define S_ISGID 0002000    /* set group id on execution */
#ifndef __BSD_VISIBLE
#define S_ISTXT 0001000    /* sticky bit */
#endif

int main()
{
  if(chmod("file" , 0777) < 0 )  
  {
     printf("change mode of file FILE failed \n");
     return -1;
  }
  printf("Chmod system call successful \n");
  return 0;
}