Read the output of perldoc -f -X, and look at the "-t" function. Here's an example of how it would work for your case (I'm using bash-shell style quotations on a perl one-liner): 
perl -le 'warn "stdout is NOT being redirected/piped" if(-t STDOUT); p
+rint "foo"'

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If you run that exactly as shown, you'll get the message on STDERR, but if you pipe stdout to another command, like this: 
   perl ... | grep o

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or if you redirect stdout to a file like this: 
  perl ... > foo.txt

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then you won't see any message on STDERR.

In reply to Re: Test if STDOUT is attached to console or shell redirected filehandle by graff
in thread Test if STDOUT is attached to console or shell redirected filehandle by desemondo

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