Perl错误：无法在未定义的值上调用方法“ encpass”-为什么？

| 以“ root”用户身份使用以下代码有什么问题： chpwd.pl 
#!/usr/bin/perl
use Unix::PasswdFile;

use strict;
use warnings;

$pw = new Unix::PasswdFile \"/etc/passwd\";
$pw->passwd(\"johndoe\", $pw->encpass(\"newpass\"));
$pw->commit();
undef $pw;
每当我尝试执行上述脚本时，都会出现以下错误：   无法在/var/www/chpwd.pl第5行的未定义值上调用方法“ encpass \” 我确认文件
/etc/passwd
不是空的或符号链接，它的所有权为   rw-r--r-- root：root 1022 passwd 系统中确实存在用户“ 2”。 请帮忙。谢谢。 跟踪输出（部分）： 
Unix::ConfigFile::mode(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:152):
152:        my $this = shift;
Unix::ConfigFile::mode(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:153):
153:        return $this->{mode} unless @_;
Unix::ConfigFile::new(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:64):
64:     $this->lock() or return undef;
Unix::ConfigFile::lock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:165):
165:        my $this = shift;
Unix::ConfigFile::lock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:167):
167:        return 1 if ($this->locking eq \"none\");
Unix::ConfigFile::locking(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:127):
127:        my $this = shift;
Unix::ConfigFile::locking(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:129):
129:        return $this->{locking} unless @_;
Unix::ConfigFile::lock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:168):
168:        return 0 if $this->{locked};
Unix::ConfigFile::lock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:169):
169:        if ($this->locking eq \"flock\") {
Unix::ConfigFile::locking(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:127):
127:        my $this = shift;
Unix::ConfigFile::locking(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:129):
129:        return $this->{locking} unless @_;
Unix::ConfigFile::locking(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:127):
127:        my $this = shift;
Unix::ConfigFile::locking(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:129):
129:        return $this->{locking} unless @_;
Unix::ConfigFile::lock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:174):
174:        my $fh = new IO::File $this->lockfile, O_CREAT|O_EXCL|O_RDWR;
Unix::ConfigFile::lockfile(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:145):
145:        my $this = shift;
Unix::ConfigFile::lockfile(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:146):
146:        @_ ? $this->{lockfile} = shift : $this->{lockfile};
IO::File::new(/usr/lib/perl/5.10/IO/File.pm:35):
35:     my $type = shift;
IO::File::new(/usr/lib/perl/5.10/IO/File.pm:36):
36:     my $class = ref($type) || $type || \"IO::File\";
IO::File::new(/usr/lib/perl/5.10/IO/File.pm:37):
37:     @_ >= 0 && @_ <= 3
38:     or croak \"usage: new $class [FILENAME [,MODE [,PERMS]]]\";
IO::File::new(/usr/lib/perl/5.10/IO/File.pm:39):
39:     my $fh = $class->SUPER::new();
IO::Handle::new(/usr/lib/perl/5.10/IO/Handle.pm:54):
54:     my $class = ref($_[0]) || $_[0] || \"IO::Handle\";
IO::Handle::new(/usr/lib/perl/5.10/IO/Handle.pm:55):
55:     @_ == 1 or croak \"usage: new $class\";
IO::Handle::new(/usr/lib/perl/5.10/IO/Handle.pm:56):
56:     my $io = gensym;
Symbol::gensym(/usr/share/perl/5.10/Symbol.pm:23):
23:     my $name = \"GEN\" . $genseq++;
Symbol::gensym(/usr/share/perl/5.10/Symbol.pm:24):
24:     my $ref = \\*{$genpkg . $name};
Symbol::gensym(/usr/share/perl/5.10/Symbol.pm:24):
24:     my $ref = \\*{$genpkg . $name};
Symbol::gensym(/usr/share/perl/5.10/Symbol.pm:25):
25:     delete $$genpkg{$name};
Symbol::gensym(/usr/share/perl/5.10/Symbol.pm:26):
26:     $ref;
IO::Handle::new(/usr/lib/perl/5.10/IO/Handle.pm:57):
57:     bless $io, $class;
IO::File::new(/usr/lib/perl/5.10/IO/File.pm:40):
40:     if (@_) {
IO::File::new(/usr/lib/perl/5.10/IO/File.pm:41):
41:     $fh->open(@_)
42:         or return undef;
IO::File::open(/usr/lib/perl/5.10/IO/File.pm:52):
52:     @_ >= 2 && @_ <= 4 or croak \'usage: $fh->open(FILENAME [,MODE [,PERMS]])\';
IO::File::open(/usr/lib/perl/5.10/IO/File.pm:53):
53:     my ($fh, $file) = @_;
IO::File::open(/usr/lib/perl/5.10/IO/File.pm:54):
54:     if (@_ > 2) {
IO::File::open(/usr/lib/perl/5.10/IO/File.pm:55):
55:     my ($mode, $perms) = @_[2, 3];
IO::File::open(/usr/lib/perl/5.10/IO/File.pm:56):
56:     if ($mode =~ /^\\d+$/) {
IO::File::open(/usr/lib/perl/5.10/IO/File.pm:57):
57:         defined $perms or $perms = 0666;
IO::File::open(/usr/lib/perl/5.10/IO/File.pm:58):
58:         return sysopen($fh, $file, $mode, $perms);
Unix::ConfigFile::lock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:175):
175:        return 0 unless defined($fh);
Unix::ConfigFile::new(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:104):
104:        my $this = shift;
Unix::ConfigFile::new(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:106):
106:        $this->unlock() or croak \"Can\'t unlock file: $!\";
Unix::ConfigFile::unlock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:184):
184:        my $this = shift;
Unix::ConfigFile::unlock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:193):
193:        return 1 if ($this->locking eq \"none\");
Unix::ConfigFile::locking(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:127):
127:        my $this = shift;
Unix::ConfigFile::locking(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:129):
129:        return $this->{locking} unless @_;
Unix::ConfigFile::unlock(/usr/local/share/perl/5.10.1/Unix/ConfigFile.pm:194):
194:        return 0 unless $this->{locked};
Carp::croak(/usr/share/perl/5.10/Carp.pm:44):
44: sub croak   { die  shortmess @_ }
Carp::shortmess(/usr/share/perl/5.10/Carp.pm:29):
29: sub shortmess { goto &shortmess_jmp }
Carp::shortmess_real(/usr/share/perl/5.10/Carp/Heavy.pm:51):
51:     local @CARP_NOT = caller();
Carp::shortmess_real(/usr/share/perl/5.10/Carp/Heavy.pm:52):
52:     shortmess_heavy(@_);
Carp::shortmess_heavy(/usr/share/perl/5.10/Carp/Heavy.pm:241):
241:      return longmess_heavy(@_) if $Verbose;
更新： 上面的脚本可以在我的本地计算机上完美运行，而不是在服务器计算机上。     
2020-02-04 3 条评论
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没有找到相关结果

    已邀请:

    届甸衬丝蚕

            你应该用 
    use strict;
use warnings;
    总是。这样做，您可能会发现以前没有注意到的错误。 似乎“ 5”未初始化，这意味着“ 6”声明已失败。但是，这样做似乎不太可能，因为您应该有一个
    /etc/passwd
    文件，并且以root身份可以读取该文件。您可以轻松地通过以下方法进行检查： 
    die \"Failed to read PW\" unless (defined $pw);
    \“ johndoe \”是现有用户吗？如果不是，我怀疑方法“ 9”将失败。 ETA：由于跟踪显示锁定错误，也许文件正在被另一个进程使用，因此无法锁定/解锁？     
    2020-02-04 0 0
    分享

    剃摧庭峨僳

            显然，构造函数返回
    undef
    而不是新创建的对象。这是构造函数的一部分（在
    ConfigFile.pm
    中）： 
    # Get a filehandle
my $fh = new IO::File $this->filename, $this->mode;
return undef unless defined($fh);
$this->fh($fh);

# Do file locking - this must happen before read is called or we could
# end up with stale data in memory
if ($this->mode eq \"r\") {
  $this->lock(\"shared\") or return undef;
}
else {
  $this->lock() or return undef;
}

# Initialize object structure from the file
if (exists $opt{readopts}) {
  $this->read($this->fh, $opt{readopts}) or return undef;
}
else {
  $this->read($this->fh) or return undef;
}
return $this;
    您可以自己跟踪它，并查看它进入哪个分支。     
    2020-02-04 0 0
    分享
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