I usually use a module such as File::MMagic.

I think you can check the first few bytes/characters of the file, to see whether they're simple text, or .DOC format. It appears that the first few characters in a Word .DOC file are ÐÏࡱá, which do not in general resemble what you find in text files. I don't know how reliable this is, but my guess is that Word docs will have some odd characters in them early on, and that could be a way of identifying the type independent of the extension.

use File::MMagic;

my $path='/path/to/file.doc';

my $mm= new File::MMagic; #use internal magic file
my $t = $mm->checktype_filename("$path");

# $t holds mime type- doesn't matter what the file extension or no ext
+ension is
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Dear Monks
'MMagic' as well as 'file <namefile>' (on Linux) are really good solutions
Thanks to all for the suggestions

Regards,
Sandeep