if ( $#ARGV < 0 ){
        print "请输入一个日期参数\n";
        exit(-1);
    }
  $var = $ARGV[0];
print "\$var is $var\n";
if ($var =~/fred/) {
print "fred\n";
}
elsif ($var =~/red/) {
print "red\n";
}
else  {
print "black\n";
}