This avoids the error for me: 
my $cmd = 'find . -type f \( -perm -0020 -o -perm -0004 -o -perm -0002
+ -o -perm -0001 -o -perm -1000 \) -ls';
my $out = "output.txt";
open (MYFILE,"> $out");
print MYFILE `$cmd`;

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In reply to Re: Problem with Parentheses by toolic
in thread Problem with Parentheses by jjoyce

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