      Linux    
  ,     ,  -
   .      -
       (      ,
   ).      -
     (,     ).
         (
 ,        ,   -
,  -  ).        
 (   ).

       . ,  
 root,       (.  " -
  "  11)       -
,      .

_^^^k    chmod: ""  , "" - .  
^|^^^ chmod  ,     (owner),    .  -
^^^^      (other),     u (user).

^^^k        setuld-  setgid-,  root. -

^^^^  ,  setuid-   
'Wjaur    root,      ,   
^       .     ,     ,   -
  ( ,    ).  
   setgid-,   root.
        ,  
  ,     setuid-  setgid-, -
       root. - -
         -
     .   setuid  
   "   "  11.

  setuid  setgid

     setuid ("set user ID"   
) ,  ,    .
,    setuid-,      ,
        ,      
 . ,  setgid ("set group ID"   
) ,  ,  ,   , 
  .  Is   setuid  s     -
 , a setgid   s      :

$ Is -I program!

-rwxr-xr-x   1 alex     pubs       15828 Nov 5 06:28 program!
$ chmod u+s programi
$ Is -1 programi

-rwsr-xr-x   1 alex     pubs       15828 Nov 5 06:28 programi
$ chmod g+s programi
$ Is -1 programi

-rwsr-sr-x   1 alex     pubs       15828 Nov 5 06:28 programi

 6.   Linux                                               209