This example worked, but I wonder whether it worked by accident, or whether this is really portable: 

perl -lwe 'my $h1=*STDOUT; open(my $h2, ">", "tmp/xx1.txt") or die; $h
+1 eq *STDOUT && print 1; $h2 eq *STDOUT && print 2'

[download]
This prints 1.

Background of the question: I have a variable containing a file handle. Depending on which branch the program takes, this variable is either initialized by $fh=*STDOUT or by open($fh,'>',$filename). At some later point in the program, I want to close $fh unless it is connected to STDOUT. The question is how to test this in a portable way.

Using -t $fh is not a solution, because this would test whether $fh is connected to a terminal, which is something different. By experimenting, I found that <c>$f eq *STDOUT<c> seems to do the job. However, doing string equality on a file handle looks a bit arcane to me.

BTW, the test for equality will be done in the same package than the assignment of the file handle (this might be relevant for the way the handle is turned into a string by the equality operator).

-- 
Ronald Fischer <ynnor@mm.st>

In reply to Testing whether a file handle is attached to STDOUT by rovf

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