In PowerShell, checking if a variable is null (or in PowerShell terms, $null) is a fundamental task in scripting, especially when dealing with the output of
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。
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 is empty or null. So the question now is, how to check it? Well, belo...
if($null-ne$path-and(Test-Path-Path$path) ) -or -or可讓您指定兩個表示式,並在其中一個$true為 時傳$true回 。 PowerShell複製 if($age-le13-or$age-ge55) 就像運算子一-and樣,評估會從左到右進行。 除了第一個部分是$true,則整個語句是$true,而且不會處理表達式的其餘部分。
# If npm install fails, the node_modules directory is removednpm install ||Remove-Item-Recurse./node_modules 有关详细信息,请参阅About_Pipeline_Chain_Operators。 范围运算符.. 范围运算符可用于表示顺序整数或字符的数组。 范围运算符联接的值定义了范围的开始值和结束值。
Microsoft.PowerShell_profile.ps1: Cannot dot-source this command because it was defined in a different language mode. To invoke this command without importing its contents, omit the '.' operator. I... Thanks All for your help! I had an internal discussion wi...
# Execute the SQL command with retry logic$connection= GiveMeConnectionSource$connectionStringif($connection-eq$null){Write-Host"It is not possible to connect to the database"exit;}ExecuteWithRetry 1$connection"WAITFOR DELAY '00:00:40'"$connection.Close(...
[System.ComponentModel.TypeConverter(typeof(Microsoft.Azure.PowerShell.Cmdlets.EventGrid.Models.IsNullOrUndefinedFilterTypeConverter))]publicinterfaceIIsNullOrUndefinedFilter:Microsoft.Azure.PowerShell.Cmdlets.EventGrid.Models.IFilter Attributes TypeConverterAttribute ...
{#Check the SocketErrorCode to see if it's the expected exceptionif($_.Exception.SocketErrorCode-eq[System.Net.Sockets.SocketError]::AddressAlreadyInUse) { Log"Port$PortNumberis in use."}else{ Log"SocketException on port${PortNumber}:$($_.Exception)"} } }$null}Test-PortAvailability12179...
!($var) 判断目录是否存在(也可以判断文件) if ( Test-Path c:\RZY ) { echo 1 } else { echo 2 } switch 与 linux的case作用一样 Switch($num){1{表达式}2{表达式}} 4、类似awk的用法(取本机第一个IP): %{$_.split("-")[0]}: 表示 ("-") 为指定分隔符 "-" ; [0] 取第一个;[...