It depends on what do you mean by filehandle is in fact STDOUT. E.g. consider the following: 

$ perl -E'open my $foo, "<&=1"; say $foo->fileno; say $foo == \*STDOUT
+ ? "STDOUT" : "Not STDOUT"'
1
Not STDOUT

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In reply to Re: check if a filehandle is STDOUT when using use strict; by zwon
in thread check if a filehandle is STDOUT when using use strict; by ISAI student

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