Here's a very trivial BF interpreter. Its written in as few lines as possible while trying to keep it readable. It expects BF code on standard input.
#!/usr/bin/perl

$cd .= $_ while (<STDIN>);

sub get_char {
    exit if ($ch_ptr == length($cd));
    return substr($cd, $ch_ptr++, 1);
}

while (1) {
    $ch = get_char;
    $cell[$cl_ptr]++ if ($ch eq '+');
    $cell[$cl_ptr]-- if ($ch eq '-');
    (($_ = chr($cell[$cl_ptr])) && print) if ($ch eq '.');
    $cl_ptr++ if ($ch eq '>');
    $cl_ptr-- if ($ch eq '<');
    if ($ch eq ',') {
        $inp_ch = getc(STDIN);
        $cell[$cl_ptr] = ord($inp_ch);
    } elsif ($ch eq '[') {
        ($ch_ptr = index($cd, ']', $ch_ptr)) if ($cell[$cl_ptr] == 0);
    } elsif ($ch eq ']') {
        ($ch_ptr = rindex($cd, '[', $ch_ptr)) if ($cell[$cl_ptr] != 0)
+;
    }
}

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In reply to BF Interpreter by aweeraman

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