,     ,  
  (   )    
 .    (,    )  
    .      HOME (
  )  PATH (,        -
      ).    -
   (  )    ; -
   ,     .

         ,
        , -
   /etc/profile.     ,  
      ,    " 
() " . 9.1.      , -
 ,    .      -
 .        .

        . 
     (, 1, ?  #)   ( 
 )       (, $1, $?  $#). -
         
. ,          -
    .    -
      ,     -
   .  ,    -
   ,    , 
         -
   .     set (. 
"set:    "    ),  -
     .

,  

  ,   ,    -
    ,      . -
       person   
 alex:

$ person=alex
$ echo person

person
$ echo $person

alex

     bash      
      TAB.    echo 
    ,       -
.

    ,  person    alex.
 person   person.     -
 ,        ($).  echo $person 

 9.  II: Bourne Again Shell                                            303