未初始化值$domain在级联(.)中的使用或串

Question

我今天写了剧本。这样做的目的是自动向Apache添加新的虚拟主机。应该使用以下命令执行脚本：

./new_vhost.pl --add --domain google.com --client google. 

然而，它不能很好地工作，相反，它会给我带来错误

未初始化值$domain在级联(.)中的使用或串

你们以前有过这种经历吗？我在想原因是“。”不过，在google.com中，我对此并不十分肯定。我仍然在谷歌上寻找答案，但不幸的是，没有什么能帮我解决这个问题。

代码：

#!/usr/bin/perl

use strict;
use warnings;
use Getopt::Long;
use Cwd;
use POSIX "strftime";

my $dir = getcwd;
my $conf = 'test.conf';

my $domain = undef;
my $client = undef;
my $help = undef;
my $ltime = undef;

if (-e $conf) {
        sub usage {
                die "Usage: $0 [--add | --remove] [--domain google.com] [--client google].\n";
        }

        usage unless @ARGV > 3;
        GetOptions (
                'add' => \&add_vhost,
#               'remove' => \&rem_vhost,
                'domain=s' => \$domain,
                'client=s' => \$client,
                'help' => \&usage
        ) || usage;

        $domain = lc($domain);
        $client = uc($client);
        $ltime = localtime;

        sub add_vhost {
                open (CONF, ">>$conf") || die "ERROR: unable to open $conf.\n";
                print CONF "#***** Start of configuration for $domain. *****#";
                print CONF "\n# Domain: $domain\n";
                print CONF "# Client: $client\n";
                print CONF "# Date: $ltime\n";
                print CONF "<VirtualHost *:1111>\n";
                print CONF "    ServerAdmin admin\@$domain\n";
                print CONF "    DocumentRoot /var/www/html/$domain\n";
                print CONF "    ServerName $domain\n";
                print CONF "    ServerAlias www.$domain\n";
                print CONF "    ErrorLog /var/log/httpd/$domain/$domain-error_log\n";
                print CONF "    CustomLog /var/log/httpd/$domain/$domain-access_log common\n";
                print CONF "</VirtualHost>\n";
                print CONF "#***** End of configuration for $domain. *****#\n";
                close CONF;
                if ($? != 0) {
                        die "Error: unable to create a new configuration.\n";
                } else {
                        print "OK: new configuration for $domain has been added.\n";
                }
        }
} else {
        die "ERROR: $conf not found.\n";

}

错误：

Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 37.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 38.
Use of uninitialized value $client in concatenation (.) or string at ./new_vhost.pl line 39.
Use of uninitialized value $ltime in concatenation (.) or string at ./new_vhost.pl line 40.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 42.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 43.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 44.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 45.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 46.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 46.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 47.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 47.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 49.
Use of uninitialized value $domain in concatenation (.) or string at ./new_vhost.pl line 54.
OK: new configuration for  has been added.

运行脚本后的test.conf。

#***** Start of configuration for . *****#
# Domain:
# Client:
# Date:
<VirtualHost *:1111>
    ServerAdmin admin@
    DocumentRoot /var/www/html/
    ServerName
    ServerAlias www.
    ErrorLog /var/log/httpd//-error_log
    CustomLog /var/log/httpd//-access_log common
</VirtualHost>
#***** End of configuration for . *****#

但我以为会发生这样的事..。

#***** Start of configuration for google.com. *****#
# Domain: google.com
# Client: GOOGLE
# Date: Tue Apr  8 17:27:39 2014
<VirtualHost *:1111>
    ServerAdmin admin@google.com
    DocumentRoot /var/www/html/google.com
    ServerName google.com
    ServerAlias www.google.com
    ErrorLog /var/log/httpd/google.com/google.com-error_log
    CustomLog /var/log/httpd/google.com/google.com-access_log common
</VirtualHost>
#***** End of configuration for google.com. *****#

Answer 1

当GetOptions试图调用您的add_vhost时，可能不会初始化变量$domain和$client。

您可以将代码更改为

my $add = undef;

...

GetOptions (
    'add' => \$add,
...

if ($add) {
    add_vhost();
}

...

顺便说一句，最好将add_vhost的定义从该条件语句中移出，并将这些信息(如$domain作为参数传递给add_vhost，而不是使用全局变量)。

Answer 2

#!/usr/bin/perl

use strict;
use warnings;
use Getopt::Long;
use Cwd;
use POSIX "strftime";

my $dir = getcwd;
my $conf = 'test.conf';

my $domain = undef;
my $client = undef;
my $help = undef;
my $ltime = undef;
my $to_add_vhost = undef;

if (-e $conf) {
        sub usage {
                die "Usage: $0 [--add | --remove] [--domain google.com] [--client google].\n";
        }

        usage unless @ARGV > 3;
        GetOptions (
                'add' => \$to_add_vhost,
#               'remove' => \&rem_vhost,
                'domain=s' => \$domain,
                'client=s' => \$client,
                'help' => \&usage
        ) || usage;

        $domain = lc($domain);
        $client = uc($client);
        $ltime = localtime;

    &add_vhost if (defined $to_add_vhost);

        sub add_vhost {
                open (CONF, ">>$conf") || die "ERROR: unable to open $conf.\n";
                print CONF "#***** Start of configuration for $domain. *****#";
                print CONF "\n# Domain: $domain\n";
                print CONF "# Client: $client\n";
                print CONF "# Date: $ltime\n";
                print CONF "<VirtualHost *:1111>\n";
                print CONF "    ServerAdmin admin\@$domain\n";
                print CONF "    DocumentRoot /var/www/html/$domain\n";
                print CONF "    ServerName $domain\n";
                print CONF "    ServerAlias www.$domain\n";
                print CONF "    ErrorLog /var/log/httpd/$domain/$domain-error_log\n";
                print CONF "    CustomLog /var/log/httpd/$domain/$domain-access_log common\n";
                print CONF "</VirtualHost>\n";
                print CONF "#***** End of configuration for $domain. *****#\n";
                close CONF;
                if ($? != 0) {
                        die "Error: unable to create a new configuration.\n";
                } else {
                        print "OK: new configuration for $domain has been added.\n";
                }
        }
} else {
        die "ERROR: $conf not found.\n";

}

Answer 3

我建议您进行一些样式更改，以清理您的代码。

• 当检查错误时，die立即而不是在else之后。
• 您可以在实际的子例程调用中声明GetOptions的参数，以简化操作。
• 在打印一个大文本块时考虑使用HERE_DOC。
• 在调用@ARGV之前对GetOptions进行错误检查是不必要的。让GetOptions通过拥有所需的参数来处理这个问题。目前，在有效的调用方法--domain=value --client=value' because only 2 elements will be in@ARGV` ` is 4下，您将失败。

这会将您的代码清理为以下内容：

#!/usr/bin/perl

use strict;
use warnings;
use autodie;

use Getopt::Long;
use Cwd;
use POSIX "strftime";

my $dir = getcwd;
my $conf = 'test.conf';

die "ERROR: $conf not found.\n" if ! -e $conf;

sub usage {
    die "Usage: $0 [--add | --remove] [--domain google.com] [--client google].\n";
}

GetOptions(
    'add'      => \my $add,
#   'remove'   => \&rem_vhost,
    'domain=s' => \my $domain,
    'client=s' => \my $client,
    'help'     => \&usage
) or usage();

$domain = lc($domain);
$client = uc($client);
my $ltime = localtime;

if ($add) {
    add_vhost();
}

sub add_vhost {
    open my $fh, '>>', $conf;

    print $fh <<"END_CONF";
#***** Start of configuration for $domain. *****#
# Domain: $domain
# Client: $client
# Date: $ltime
<VirtualHost *:1111>
    ServerAdmin admin\@$domain
    DocumentRoot /var/www/html/$domain
    ServerName $domain
    ServerAlias www.$domain
    ErrorLog /var/log/httpd/$domain/${domain}-error_log
    CustomLog /var/log/httpd/$domain/${domain}-access_log common
</VirtualHost>
#***** End of configuration for $domain. *****#
END_CONF

    if ($? != 0) {
        die "Error: unable to create a new configuration.\n";
    } else {
        print "OK: new configuration for $domain has been added.\n";
    }
}