Perl警告：使用带有多个点的字符串时使用未初始化的值（。）

Question

我是Perl脚本的新手。我正在尝试远程SSH到Linux机器和我的代码如下：

my $hostname = "something.xyz.abc.com";
my $uid = "userid";
my $pwd = "pass";

my $ssh = Net::SSH::Perl->new($hostname);
$ssh->login($uid, $pwd);
my($stdout, $stderr, $exit) = $ssh->cmd("ls -l");
print $stdout;

我看到

的原因是什么

  

“使用带有多个点的字符串时使用未初始化的值（。）”

警告？如何避免/抑制它？这些多点是否会产生问题？

具体的错误信息是：

Use of uninitialized value in concatenation (.) or string at C:/Dwimperl/perl/site/lib/Net/SSH/Perl/Key.pm line 13, <$fh> line 57.
Use of uninitialized value $blob in split at C:/Dwimperl/perl/site/lib/Net/SSH/Perl/Key.pm line 41, <$fh> line 59.
Use of uninitialized value $ssh_name in hash element at C:/Dwimperl/perl/site/lib/Net/SSH/Perl/Key.pm line 42, <$fh> line 59.
Use of uninitialized value in subroutine entry at C:/Dwimperl/perl/site/lib/Net/SSH/Perl/Key.pm line 45, <$fh> line 59.