perl - 如何使用 Perl 为 DNS 查找配置“检查错误”？

Question

我有一个脚本，允许我在输入将转发到 DNS 服务器的 IP 地址后查找主机名。

但是，即使一切正常，如果找不到 DNS，程序似乎也无法打印出我想要的错误示例。

代码：

#!/usr/bin/perl

use IO::Socket;
use warnings;
use strict;
use Term::ANSIColor;
use Socket;
use Sys::Hostname;

print "\nYou are now in Show DNS IP Address!\n\n";

print "*************\n";
print "|DNS Address|\n";
print "*************\n";

print "\nPlease enter a hostname that you wish to view\n\n";
print "\n\nEnter the hostname of Choice Here: ";
my $userchoice =  <>;
chomp ($userchoice);

my $host = hostname();

my $hostname = $userchoice;

my $packed_ip = gethostbyname("$hostname");

my $ip_address = inet_ntoa($packed_ip) or system("clear"), system("/root/Desktop 
/showdns.pl"), die("Can't resolve $hostname: $!\n ,try again");

my $coloredText = colored($name, 'bold underline blue');
print "\n\nThe hostname IP address is: $coloredText\n\n";

print "Press enter to go back to the main menu\n\n";
my $userinput2 = &lt;&gt;;
chomp ($userinput2);

system("clear");
system("/root/Desktop/simpleip.pl");

有人可以就代码提供一些建议吗？

Answer 1

不要滥用|运算符来执行一系列操作。它没有做你想做的事，尽管我不清楚你想要什么。什么时候应该调用这两个系统调用？关于成功或失败？

如果应该在 die() 被调用时完成，你可以这样做：

my $i_addr = scalar(gethostbyname($hostname || 'localhost'))
    or system("clear"), system("/root/Desktop/showdns.pl"), die("Can't resolve $hostname: $!\n ,try again");
my $name = inet_ntoa($i_addr);

my $i_addr = scalar(gethostbyname($hostname || 'localhost'));
if ( $i_addr ) {
    system("clear");
    system("/root/Desktop/showdns.pl");
    die("Can't resolve $hostname: $!\n ,try again");
}
my $name = inet_ntoa($i_addr);

（修复了inet_ntoa的误用；您需要先验证gethostbyname是否成功，然后才能调用它。）