What do you mean?!

Save this code to a file and test it.

#!/usr/bin/perl -wl
use strict;
open my $fh, '>', '/tmp/test.log' or die $!;
print $fh 'STDIN ', ( -t STDIN ? 'IS' : 'is NOT' ), ' available' or di
+e $!;
close $fh or die $!;
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In a cron job -t would evaluate to false which in my case would mean my script would think info is being piped to it when I have a commandline option -logfile <file> being used to specify input.