我写了一个函数来检查主机是在线还是离线，并返回$true或$false。这个函数工作得很完美，我想通过观察来改进它如果可以删除脚本范围的变量，如$Script:arrayCanPingResult和$script:tmpPingCheckServers。
为什么我想要这个?当我在foreach循环中调用函数时，我通常使用开关-Remember，因此它不会检查同一主机两次。为了能够正确地使用这个，我必须开始我所有的脚本，在那里我通过声明两个变量为空($Script:arrayCanPingResult=$script:tmpPingCheckServers=@{})来使用这个函数。我可以想象人们忘记把第一行放在他们的脚本中，当在PowerShell ISE编辑器中多次测试时，当主机已经在ISE中检查过一次时，它不会在第二次运行时再次进行测试(F5)。
是否有一种方法可以避免在这种情况下使用脚本范围的变量?所以我们不需要在新脚本开始时将它们声明为空?如果这是可能的，那就太好了，因为这样我们就可以在自定义模块中包含这个函数。
一如既往，感谢您的建议或帮助。和你们在一起我真的学到了很多。# Function to check if $Server is online
Function Can-Ping ($Server,[switch]$Remember) {
$PingResult = {
# Return $true or $false based on the result from script block $PingCheck
foreach ($_ in $Script:arrayCanPingResult) {
# Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: $_ " -ForegroundColor Green
if ($Server -eq $($_.Split(",")[0])) {
#Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: We will return $($_.Split(",")[1])" -ForegroundColor Green
return $($_.Split(",")[1])
}
}
}
$PingCheck = {
$Error.Clear()
if (Test-Connection -ComputerName $Server -BufferSize 16 -Count 1 -ErrorAction 0 -quiet) { # ErrorAction 0 doesn't display error information when a ping is unsuccessful
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: Ping test ok" -ForegroundColor Gray; $Script:arrayCanPingResult+=@("$Server,$true"); return
}
else {
$Error.Clear()
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: Ping test FAILED" -ForegroundColor Gray
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: Flushing DNS" -ForegroundColor Gray
ipconfig /flushdns | Out-Null
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: Registering DNS" -ForegroundColor Gray
ipconfig /registerdns | Out-Null
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: NSLookup" -ForegroundColor Gray
nslookup $Server | Out-Null # Suppressing error here is not possible unless using '2> $null', but if we do this, we don't get $true or $false for the function so '| Out-Null' is an obligation
if (!$?) {
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: NSlookup can't find the host '$Server', DNS issues or hostname incorrect?" -ForegroundColor Yellow
# Write-Host $Error -ForegroundColor Red
if ($SendMail) {
Send-Mail $MailTo "FAILED Ping test" "$(Get-TimeStamp) NSlookup can't find the host '$Server', hostname incorrect or DNS issues?" "<font color=`"red`">$error</font>"
}
$script:arrayCanPingError += "ERROR | $(Get-TimeStamp) Ping test failed: NSlookup can't find the host '$Server', hostname incorrect or DNS issues?$error"
$script:HTMLarrayCanPingError += "ERROR | $(Get-TimeStamp) Ping test failed:<br>NSlookup can't find the host '$Server', hostname incorrect or DNS issues?<br><font color=`"red`">$error</font>"
$Script:arrayCanPingResult+=@("$Server,$false")
return
}
else {
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: Re-pinging '$Server'" -ForegroundColor Gray
if (Test-Connection -ComputerName $Server -BufferSize 16 -Count 1 -ErrorAction 0 -Quiet) {
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: Ping test ok, problem resolved" -ForegroundColor Gray
$Script:arrayCanPingResult+=@("$Server,$true")
return
}
else {
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: DNS Resolving is ok but can't connect, server offline?" -ForegroundColor Yellow
if ($SendMail) {
Send-Mail $MailTo "FAILED Ping test" "$error" "DNS Resolving is ok but can't connect to $Server, server offline?"
}
$script:arrayCanPingError += "ERROR Ping test failed: DNS Resolving is ok but can't connect to $Server, server offline?$error"
$script:HTMLarrayCanPingError += "ERROR Ping test failed: DNS Resolving is ok but can't connect to $Server, server offline?<br><font color=`"red`">$error</font>"
$Script:arrayCanPingResult+=@("$Server,$false")
return
}
}
}
}
# Call the script block $PingAction every time, unless the switch $Remember is provided, than we only check each server once
if ($Remember) {
Write-Host "$(Get-TimeStamp) $Server > Function Can-Ping: Switch '-Remember' detected" -ForegroundColor Gray
While ($tmpPingCheckServers -notcontains $Server) {
&$PingCheck
$script:tmpPingCheckServers = @($tmpPingCheckServers+$Server) #Script wide variable, otherwise it stays empty when we leave the function / @ is used to store it as an Array (table) instead of a string
}
&$PingResult
}
else {
&$PingCheck
&$PingResult
}
}
我是这样做的:
function Get-PingStatus {
param(
# Server object.
[Parameter(Mandatory=$true)]
[ValidateNotNullOrEmpty()]
$Server,
[Parameter(Mandatory=$false)]
[Bool]$UseLastPingResult = $false
)
if ( ($UseLastPingResult) `
-and (! [String]::IsNullOrEmpty($Server.LastPingResult)) ) {
# Return unmodified object if LastPingResult property is not empty.
return $Server
}
try {
$oPingResult = Test-Connection -ComputerName $Server.Name `
-BufferSize 16 -Count 1 -ErrorAction Stop
$Server.LastPingResult = "success"
# And just in case.
$Server.IPV4Address = $oPingResult.IPV4Address
}
catch {
$Server.LastPingResult = "failure"
}
return $Server
}
对象输入，对象输出。一般来说，这是编写PowerShell函数的最佳方法，因为:1)它符合常规cmdlet的功能，2)它可以帮助您保持代码简单易读。
使用ErrorAction -Stop和try…finally也比ErrorAction -SilentlyContinue更好，之后检查一些变量
现在让我们假设$cServerNames是一个服务器名称或任何可以解析为IP地址的集合。示例:@("server1", "server2", "1.2.3.4", "webserver.example.com") .
# Converting strings to objects.
$cServers = @()
foreach ($sServerName in $cServerNames) {
$oServer = New-Object PSObject -Property @{
"Name" = $sServerName;
"IPV4Address" = $null;
"LastPingResult" = $null;
}
$cServers += $oServer
}
# Now we can iterate objects and update their properties as necessary.
foreach ($oServer in $cServers) {
$oServer = Get-PingStatus -Server $oServer -UseLastPingResult
if ($oServer.LastPingResult -eq "success") {
# Do something.
} else {
# Do something else like an error message.
}
}
您可以添加任何您想要的诊断输出，但我建议您使用Write-Output和/或Write-Error而不是Write-Host。
最后，请注意，在大多数情况下，ping在生产代码中实际上是无用的。这是多余的，无论主人是否回复都不能证明什么。例如，ping可能没问题，但由于某种原因，在随后的get - wmiobject查询中会出现异常。如果您执行ping是出于性能原因(为了节省时间)，您应该考虑通过后台作业或工作流并行运行脚本块。