correct isatty usage

[news]

In article <18432 at adm.BRL.MIL> Pabbisetty.henr at xerox.com (Nagesh Pabbisetty) writes:
>> I am trying to use this invokation:
>>
>>         if (isatty (stdin))
>
>
>Use the following segment of code:
>
>	if (isatty(fileno(stdin))) {
>  	        printf("Hello> ");
>   	       fflush(stdout);
>   	       }

Now my question is, how would you do this in a script?  Either C or Bourne.
In C shell, I have this code, but it doesn't appear to work.

if ({`test -t 0`}) then
    echo -n "==> "
else
    echo -n "--> "
endif

It should print "-->" if stdin isn't coming from a terminal, but it doesn't
seem to work that way.  It always prints "==>".

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