in reply to Match a string only once in a file

There is also index. It returns -1 if the string is not found.

local $/;
my $contents = <IN>;
close IN;
my @found;
for (@array) {
    next if -1 == index $contents, $_;
    push @found, $_;
}

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or my @found = grep {-1 != index $content, $_} @array;

After Compline,
Zaxo

In Section Seekers of Perl Wisdom