Bareword found where operator expected

you're sure you didn't confuse the programming language?

PS: FWIW $? exists!

Or possibly you don't really ask the right question. Because something like "$?" does indeed look quite perlish. But "if ($?variable_name)" does not make much sense to me.

$? is a special variable that contains the return code or error status of that last child spawned or forked by your program, for example by a `...` backticks command or by a system command. Maybe you should explain better your question.

The script which i am looking at has both the perl and tcsh interpreter definded. I am wondering it may be a tcsh syntax then as it does not fit the context . I think it means if the variable variable_name exists get in the if condition ,looking at the context . But not sure .. Thanks

Seems you have the answer. The tcsh documentation says:

   $?name
   ${?name}
               Substitutes the string `1' if name is set, `0' if it is not.

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