setenv()
(

if [ $# -eq 2 ]
then

eval $1=$2
export $1
else

echo ": setenv  " 1>&2
fi
}

$ . .bash_profile

$ setenv TCL_LIBRARY /usr/local/lib/tcl
$ set | grep TCL_LIBRARY
TCL_LIBRARY=/usr/local/lib/tcl

      eval  bash  -
  $1=$2.   $1=$2     ($), -
       .   
     TCL_LlBRARY=/usr/local/lib/tcl, 
  .  ,    eval, 
    ,     .



    . ,    ,
     .   -
      , 
   ;       -
       .   -
           
 .

 ,       
   if...then, if...then...else  if...then...elif. 
 case    ;    
       .

    test     
.           -
   .       Linux  true -
  , a false   .

      for... in, for, until 
while.         .

  break  continue     :

break    , a continue     .

  trap  ,  Linux  -
 ,    ,     -
    .    trap , , -
 ,      .

 28.   Bourne Again Shell                                909