#!   

        -
 ,   ,      
.        -
   ,      
,    ,     (
bash).       #!,   
      ,    -
.      ,    .  
 ,       bash:

$ cat sh_script

#!/bin/bash

echo "  Bourne Again Shell."

    ,   ,   -
 ,   bash.     , -
     tcsh:

$ cat tcsh_script

#!/usr/bin/tcsh
echo "  tcsh."
set person = jenny
echo " $person"

       ,    -
 tcsh.     #!      -
 tcsh,   ,    .

  ,    ,   
:

$ cat whichshell

#!/bin/tcsh

ps -f | grep $0

$ whichshell

zach      5141 2168 0 14:36 pts/1    00:00:00 tcsh ./whichshell

zach      5143 5141 0 14:36 pts/1    00:00:00 grep ./whichshell

 -f   ps    ,   
 ,  .   $0    -
,  grep      ps -f, 
 .    :   tcsh,     grep, -
   tcsh.

   #!     ,  ,
     ,   .   #! 
   .    #!   -
  bash, ,  tcsh,      ,
    .

300  III.   Red Hat Linux