    ,    :  -
     ,     , 
      ().   
  ,     export.

   export       
        . 
         
  .

    extesti   cheese
 american,        (extesti)   -
 cheese.   extesti   subtest,  -
    .   subtest   cheese  -
  .    subtest   -
 ,   extesti,   extesti 
    cheese.

$ cat extesti

cheese=american

echo "extesti 1: $cheese"

subtest

echo "extesti 2: $cheese"

$ cat subtest

echo "subtest 1: $cheese"

cheese=swiss

echo "subtest 2: $cheese"

$ extesti

extesti 1: american

subtest 1:

subtest 2: swiss
extesti 2: american

 subtest     cheese  extesti, a extesti
   .          
  .      ,  
  subtest,    :   -
   .

 , extest2,   extesti,     
export4,     cheese    subtest:

$ cat extest2

export cheese

cheese=american

echo "extest2 1: $cheese"

subtest

echo "extest2 2: $cheese"

4     ,       -
.          .

306                                       III.   Red Hat Linux