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...
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。
Check if .txt file is empty Check if a process is running check if a process or service is hanging/not responding? Check if a text file is blank in powershell check if computer exist in ou Check if drive exists, If not map Check if Email address exists in Office 365 and if exists,...
若要建立新的變數,請使用 assignment 語句將值指派給變數。 您不需要在使用它之前宣告變數。 所有變數的預設值為$null。 若要取得 PowerShell 工作階段中所有變數的清單,請輸入Get-Variable。 變數名稱會顯示,而沒有用來參考變數的前一個貨幣符號($) 符號。
A prominent example of comparing arbitrary objects is to find out if they're null. But if you need to determine whether a variable is $null, you must put $null on the left-hand side of the equality operator. Putting it on the right-hand side doesn't do what you expect. For ex...
First positional function argument is: One Second positional function argument is: Two First named scriptblock argument is: One Second named scriptblock argument is: 4 通过此例来分析script 和function的关系。 Script由普通的Function以及其他的逻辑语句(顺序、选择、循环)组成。
If the value of the $ConfirmPreference variable is None, PowerShell never automatically prompts you before running a cmdlet or function. To change the confirming behavior for all cmdlets and functions in the session, change $ConfirmPreference variable's value. To override the $ConfirmPreference fo...
(".log","_backup.log")Copy-Item-Path$logFile-Destination$backupLogFile# Create a new empty log file$null|Set-Content-Path$logFile}# Read previous results (if exist)$previousResults= @{}if(Test-Path$resultsFile){$previousResultsJson=Get-Content$resultsFile|Out...
ToString("yyyy-MM-dd HH:mm:ss") if ($LogFile -ne $null -and $LogFile -ne [System.String]::Empty) { Out-File -Append -FilePath $LogFile -InputObject "[$TimeStamp] $Message" } if ($ConsoleOutput -eq $true) { Write-Host "[$TimeStamp] [$LogLevel] :: $Message" -Foreground...
Next, I perform a quick check to make sure my HTML element references are valid:Copy if ($tb1 -eq $null -or $tb2 -eq $null –or $add -eq $null -or $btn -eq $null) { write-host "One or more controls are null" -backgroundcolor "red" -foregroundcolor "yellow" } else { ...