 tr           ,
       .!.   , tr 
   !      2. ( -
  !      .?   .)  
  tr    abstract,    ,    -
    ,   :

$ cat abstract | tr abc 


$ tr abc ABC < abstract

 tr     .

 Ipr ("line printer"   )   , -
     ,    .    
  Ipr   ,       .  
     ,  Ipr      .
       Ipr.   -
  . 7.12 ,     Is  Ipr   
(temp)        .   temp ,
     .      
  (  temp)     .

$ Is > temp

$ Ipr temp

$ rm temp



$ Is I Ipr

$

. 7.12. 

  . 7.13     who   temp, a
      .  sort (.  "sort: 
 "  5)     ,   -
 ,     ,    ,   
   .   sort  . 7.13  
   ,   (<)     temp. -
 ,      sort,    -
 ( ) .

$ who > temp
$ sort < temp

alex       pts/4        Mar 27 12:23
alex       pts/5       Mar 27 12:33
jenny      pts/7        Mar 26 08:45
root       console      Mar 27 05:00
$ rm temp

. 7.13.      

234                                               II.   Red Hat Linux