$opt{'signal-stat'} //= exists $SIG{INFO} ? 'INFO' : 'QUIT';
$opt{markers} //= '=avg >31.73v <68.27v +50v |0';
$opt{palette} //= $opt{color} && [31, 90, 32];
-$opt{input} = @ARGV && $ARGV[0] =~ m/\A[-0-9]/ ? \@ARGV : undef;
+$opt{input} = @ARGV && $ARGV[0] =~ m/\A[-0-9]/ ? \@ARGV : undef
+ and undef $opt{interval};
my (@lines, @values, @order);