我正在尝试使用正则表达式来过滤除VMware VMX文件中的一个非常特定的文本行，我正在通过foreach循环运行，因为每个VM都有多个文件。每次循环运行时，它会将运行cat的Net::OpenSSH的输出与位于VM服务器上的文件绑定到标量变量。
我不确定这是否真的有意义。
无论如何，我遇到的问题是当脚本运行时，它与我的正则表达式中的任何内容都不匹配，它只是一个接一个地显示所有cated VMX文件。我无法弄清楚我错过了什么。
以下是我正在处理的代码示例。
sub get_virtual_machines {
my $esx_host = config_file()->{ESX}{host};
my $ssh_port = config_file()->{ESX}{port};
my $esx_user = config_file()->{ESX}{user};
my $esx_password = config_file()->{ESX}{password};
my %options = (
port => $ssh_port,
user => $esx_user,
password => $esx_password
);
my $ssh1 = Net::OpenSSH->new($esx_host, %options);
print color 'blue';
print "Collecting virtual machine data for $esx_host\n";
my @virtual_machines = $ssh1->capture('vim-cmd vmsvc/getallvms');
shift @virtual_machines;
print color 'reset';
# Filter data from ESX\ESXi output
my %virtual_machines = ();
foreach my $vm (@virtual_machines) {
# Replace "[" with "/"
$vm =~ s/\[/\//;
# Replace "]" with "/"
$vm =~ s/\]/\//;
# Match ID, NAME and VMX location
$vm =~ m/^(\d+)\s+(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s+(\D+)(\D)(\d)(\d)/x;
# Build hash table of discovered virtual machines
$virtual_machines{"$2"}{"ID"} = "$1";
$virtual_machines{"$2"}{"VMX"} = "/vmfs/volumes$3$4";
$virtual_machines{"$2"}{"Version"} = "$9";
}
undef @virtual_machines;
foreach my $vm (keys %virtual_machines) {
$vm = $ssh1->capture("cat $virtual_machines{$vm}{VMX}");
$vm =~ m/^(\bguestOSAltName\b)/x;
print "$1\n";
}
#print Dumper (\%virtual_machines);
}
有问题的部分是在“undef @virtual_machines”行之后。样品中的第38行 我的第一个目标是将该行与“guestOSAltName”这个词匹配。我想，一旦我完成了这一部分，我将再次前行，只是碰到路障。
这是一个要查看的示例VMX文件。
.encoding = "UTF-8"
config.version = "8"
virtualHW.version = "7"
pciBridge0.present = "TRUE"
pciBridge4.present = "TRUE"
pciBridge4.virtualDev = "pcieRootPort"
pciBridge4.functions = "8"
pciBridge5.present = "TRUE"
pciBridge5.virtualDev = "pcieRootPort"
pciBridge5.functions = "8"
pciBridge6.present = "TRUE"
pciBridge6.virtualDev = "pcieRootPort"
pciBridge6.functions = "8"
pciBridge7.present = "TRUE"
pciBridge7.virtualDev = "pcieRootPort"
pciBridge7.functions = "8"
vmci0.present = "TRUE"
nvram = "NS02.nvram"
deploymentPlatform = "windows"
virtualHW.productCompatibility = "hosted"
unity.customColor = "|23C0C0C0"
tools.upgrade.policy = "useGlobal"
powerType.powerOff = "default"
powerType.powerOn = "default"
powerType.suspend = "default"
powerType.reset = "default"
displayName = "NS02"
extendedConfigFile = "NS02.vmxf"
scsi0.present = "TRUE"
scsi0.sharedBus = "none"
scsi0.virtualDev = "lsilogic"
memsize = "512"
scsi0:0.present = "TRUE"
scsi0:0.fileName = "NS02.vmdk"
scsi0:0.deviceType = "scsi-hardDisk"
ide1:0.present = "TRUE"
ide1:0.clientDevice = "FALSE"
ide1:0.deviceType = "cdrom-image"
ide1:0.startConnected = "FALSE"
ethernet0.present = "TRUE"
ethernet0.virtualDev = "e1000"
ethernet0.networkName = "solignis.local"
ethernet0.addressType = "generated"
chipset.onlineStandby = "FALSE"
guestOSAltName = "Ubuntu Linux (64-bit)"
guestOS = "ubuntu-64"
uuid.location = "56 4d ab a6 1e 7b c5 43-02 45 7c 24 1f fc 28 d9"
uuid.bios = "56 4d ab a6 1e 7b c5 43-02 45 7c 24 1f fc 28 d9"
vc.uuid = "52 50 c1 4b be 91 07 d5-22 0e 86 ee db 88 6d 8a"
snapshot.action = "keep"
sched.cpu.min = "0"
sched.cpu.units = "mhz"
sched.cpu.shares = "normal"
sched.mem.minsize = "0"
sched.mem.shares = "normal"
sched.scsi0:0.shares = "normal"
bios.forceSetupOnce = "FALSE"
floppy0.present = "FALSE"
ethernet0.generatedAddress = "00:0c:29:fc:28:d9"
tools.syncTime = "FALSE"
cleanShutdown = "FALSE"
replay.supported = "FALSE"
sched.swap.derivedName = "/vmfs/volumes/4cbcad5b-b51efa39-c3d8-001517585013/NS02/NS02-510988a0.vswp"
scsi0:0.redo = ""
vmotion.checkpointFBSize = "4194304"
pciBridge0.pciSlotNumber = "17"
pciBridge4.pciSlotNumber = "21"
pciBridge5.pciSlotNumber = "22"
pciBridge6.pciSlotNumber = "23"
pciBridge7.pciSlotNumber = "24"
scsi0.pciSlotNumber = "16"
ethernet0.pciSlotNumber = "32"
vmci0.pciSlotNumber = "33"
ethernet0.generatedAddressOffset = "0"
vmci0.id = "536619225"
hostCPUID.0 = "0000000a756e65476c65746e49656e69"
hostCPUID.1 = "000006fb000408000000e3bdbfebfbff"
hostCPUID.80000001 = "00000000000000000000000120100800"
guestCPUID.0 = "0000000a756e65476c65746e49656e69"
guestCPUID.1 = "000006fb00010800800022010febfbff"
guestCPUID.80000001 = "00000000000000000000000120100800"
userCPUID.0 = "0000000a756e65476c65746e49656e69"
userCPUID.1 = "000006fb000408000000e3bdbfebfbff"
userCPUID.80000001 = "00000000000000000000000120100800"
evcCompatibilityMode = "FALSE"
ide1:0.fileName = "/usr/lib/vmware/isoimages/linux.iso"
答案 0 :(得分：5)
很难说你提供的信息，但我认为问题在于正则表达式
$vm =~ m/^(\bguestOSAltName\b)/x;
与您提供的文件不匹配，因为^断言匹配字符串的开头，而不是行的开头。由于正则表达式不匹配，$1保留了程序中较早的旧值，并将其打印出来。为安全起见，您应该在使用捕获之前检查实际匹配的正则表达式：
if ($vm =~ m/^(\bguestOSAltName\b)/x) {
print "$1\n";
}
else {
carp "Couldn't find guestOSAltName!";
}
或者通过将匹配放在列表上下文中来抓取捕获：
# $result gets $1 if the match succeeds, undef if it fails.
my ($result) = $vm =~ m/^(\bguestOSAltName\b)/x
要使^匹配行首，您需要/m修饰符，它将^$更改为按行而不是按字符串匹配：
if ($vm =~ m/^(\bguestOSAltName\b)/xm) { ... }
这就是为什么Perl最佳实践中的Damian Conway建议您总是使用/m - 因为^$ 总是直观地做你的事认为他们应该这样做。 [他实际上建议总是使用/xms。你在那里的三分之一:)]
我发现在正则表达式和其他双引号上下文中过度使用转义字符
$vm =~ s/\[/\//;
通常在单一的上下文中更好地重写：
$vm =~ s'['/';
此外，这个正则表达式很难阅读：
$vm =~ m/^(\d+)\s+(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s+(\D+)(\D)(\d)(\d)/x;
您使用的是/x标记，为什么不利用它？
$vm =~ m/^(\d+) \s+ # $1: number of some sort
(\S+) \s+ # $2: identifier we're interested in
(\S+) \s+ # $3: VMX filename part a
(\S+) \s+ # $4: VMX filename part b
(\S+) \s+ # $5: another identifier
(\D+)(\D) # $6, $7: at least two nondigits
(\d) # $8: digit
(\d) # $9: version digit
/x;
我还考虑使用命名捕获：
$vm =~ m/^(?: \d+) \s+ # number of some sort
(?<ID> \S+) \s+ # $+{ID}: identifier we're interested in
(?<VMXa> \S+) \s+ # $+{VMXa}: VMX filename part a
(?<VMXb> \S+) \s+ # $+{VMXb}: VMX filename part b
(?: \S+) \s+
(?:\D+)(?:\D) # at least two nondigits
(?:\d) # one digit
(?<VERSION> \d) # $+{VERSION}: version digit
/x;
现在，您可以使用明确，明显，自我记录的$2和$9引用来代替对$+{ID}和$+{VERSION}的隐秘引用。我已将其余的组变为非捕获组(?:regex)，但如果我想在以后捕获一个组，我可以将其变为命名捕获而不更改所有其他捕获的索引，不像与位置捕获。
命名捕获也不太可能遭受上面提到的旧值问题，其中失败的捕获使所有$1变量保持旧状态。
答案 1 :(得分：1)
如果我猜对了你想要的东西，那可能就像是
if( $vm =~ /^guestOSAltName = (.+)\n/ )
{
print "$1\n";
}
答案 2 :(得分：0)
正如@canavanin所说，问题是你有一个多行文字，所以你需要使用m//m才能让^和$表示行的开头和结尾（而是开始和结束字符串）。将变量捕获到变量也更好（更安全）（在perl> 5.10中，你也将@Potter命名为捕获）。最后，m // x非常有用，但只有在你用几行编写你的正则表达式时，为了允许注释和忘记空格，但是在一行中是没用的，并且容易出错，因为人们忘记了显式写空格\s或\s+并将实际（但由x）空格转换为真实空格。
另外正如您所说，您想要打印该行，而不仅仅是'guestOSAltName'，那么您需要捕获直到行结束：m/(^guestOSAltName .+$)/m（如果您将单行模式添加到多行//ms然后您需要使.+非贪婪.+?允许$在贪婪.+消耗之前匹配行尾。 1}}在单行模式下）
[not working code]
$vm =~ m/^(\bguestOSAltName\b)/x;
print "$1\n";
[working code]
# make list context with parentheses
(my $guest_os_alias_line) = $vm=~m/^ # start of line (using /m)
( #start capturing
guestOSAltName
\b # just in case guestOSAltName is a substring in an unwanted line
.+ # everything else in the line (not matching \n because no /s)
) # end capturing
$ # end of line (because /m)
/xm; # multiline mode
print "$guest_os_alias_line\n";
如果你有多个这样的行，那么你希望有一个多匹配模式/ g并捕获一个数组：
(my @guest_os_alias_lines) = $vm=~m/^ # start of line (using /m)
( #start capturing
guestOSAltName
\b # just in case guestOSAltName is a substring in an unwanted line
.+ # everything else in the line (not matching \n because no /s)
) # end capturing
$ # end of line (because /m)
/xmg; # multiline mode (m) and multi-matching(g)
print "@guest_os_alias_line\n"; # not needed `join ("\n",@guest_os_alias_line)` because the lines contain the `\n` already