Checking if a string is NULL or EMPTY is very common requirement in Powershell script. If we don’t do that we will end up with run time errors if we try to perform some operation on that string variable which i
PowerShell 複製 if ( $null -ne $value -and $value -ne 0 -and $value -ne '' -and ($value -isnot [array] -or $value.Length -ne 0) -and $value -ne $false ) { Do-Something } 只要您記得其他值算作$false,而不僅僅是變數具有值,使用基本if檢查就完全沒問題了。
string to System.Management.Automation.ScriptBlock Cannot use Set-Acl properly despite being file owner and being a member of Administrators Group. Cannot validate argument on parameter 'Name'. The argument is null or empty. Provide an argument that is not null or empty, and then try the ...
function Test-MrParameterValidation { [CmdletBinding()] param ( [ValidateNotNullOrEmpty()] [string[]]$ComputerName = $env:COMPUTERNAME ) Write-Output $ComputerName } 详细输出 如果要编写复杂的代码,则内联注释非常有用,但除非用户查看代码,否则不会看到它们。 以下示例中的函数在 foreach 循环内有一...
特性的值HelpMessage不应为空字符串或 null 值,因为这会导致 PowerShell 解释器在执行函数或 cmdlet 时引发错误。 方式 指定HelpMessage属性的值。 示例 错 PowerShell FunctionBadFuncEmptyHelpMessageEmpty {Param( [Parameter(HelpMessage='')] [String]$Param)$Param}FunctionBadFuncEmptyHelpMessage...
Commands Gets or sets current powershell command line. HadErrors If an error occurred while executing the pipeline, this will be set to true. HistoryString The history string to be used for displaying the history. InstanceId Get unique id for this instance of runspace pool. It is primarily...
If you simply remove the[string]type then it will work as expected: function f2 { param ( $x ) return $x } $null -eq (f2 -x $null) There is no value in declaring a parameter as type string because all classes in .Net have to derive from theObjectclass. Therefore every class impl...
If the function is invoked without pipeline input, PowerShell executes theprocessblock only once. Within a pipeline, theprocessblock executes once for each input object that reaches the function. If the pipeline input that reaches the function is empty, theprocessblock doesn't execute. ...
runspace.Open(); //Create an empty pipeline using (Pipeline pipeline = runspace.CreatePipeline()) { //Commands--获取此管道的命令集合 //AddScript(String) Adds a new script command 添加一个新的脚本命令 pipeline.Commands.AddScript(command); //合并此命令结果 //myResult:PipelineResultTypes:要重定...
Enclose the whole OPATH filter in double quotation marks " ". If the filter contains system values (for example,$true,$false, or$null), use single quotation marks ' ' instead. Although this parameter is a string (not a system block), you can also use braces { }, but only if the fi...