Any condition other than zero, false, blank are considered as true only. Here, when it starts execution it checks for cond1 as if it is true or false, based on the value it will execute the statement block if cond1 is true it will execute statement1 and PowerShell exit. But if cond1 is false, then it will check else if block cond2, if cond2 is true then statement2 will be executed.
If cond1 and cond2 both are false or none of the condition is true then else statement will be executed. The above code will print output according to today. If we want to check if the database server is up or down checking if the database is running or not then we can use if statement.
So if the database is down then run any service or command to up database. This will be completely automated which will check all the time database status. Many times because of the heavy load on a server it stops working, so to check the threshold load capacity of the server we can use Powershell if condition and inside condition we can write our required statements.
With the above example, we are clear that if a statement can play a very crucial role in the real software world. This is a guide to If Statement in PowerShell. You can also go through our other related articles to learn more—. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services.
Privacy policy. Describes a language command you can use to run statement lists based on the results of one or more conditional tests. You can use the If statement to run code blocks if a specified conditional test evaluates to true.
You can also specify one or more additional conditional tests to run if all the prior tests evaluate to false. Finally, you can specify an additional code block that is run if no other prior conditional test evaluates to true.
You can use multiple Elseif statements to chain a series of conditional tests. That isn't the case in PowerShell. You must provide a full scriptblock with braces for it to work correctly. The most common use of the if statement for is comparing two items with each other. PowerShell has special operators for different comparison scenarios. When you use a comparison operator, the value on the left-hand side is compared to the value on the right-hand side.
The -eq does an equality check between two values to make sure they're equal to each other. One possible use case is to check the status of a value before you take an action on it. You could get a service and check that the status was running before you called Restart-Service on it. By placing your known value on the left, it makes that mistake more awkward to make. Many operators have a related operator that is checking for the opposite result. Use this to make sure that the action only executes if the value isn't 5.
A good use-cases where would be to check if a service was in the running state before you try to start it. These are inverse variations of -eq. I'll group these types together when I list variations for other operators.
These operators are used when checking to see if a value is larger or smaller than another value. PowerShell has its own wildcard-based pattern matching syntax and you can use it with the -like operator. These wildcard patterns are fairly basic. It's important to point out that the pattern matches the whole string. The -match operator allows you to check a string for a regular-expression-based match. Use this when the wildcard patterns aren't flexible enough for you. A regex pattern matches anywhere in the string by default.
So you can specify a substring that you want matched like this:. Regex is a complex language of its own and worth looking into. I talk more about -match and the many ways to use regex in another article. You may use this if you're working with classes or accepting various objects over the pipeline. You could have either a service or a service name as your input. Then check to see if you have a service and fetch the service if you only have the name.
This is handled slightly differently when working with a collection. This still works correctly in a if statement. There's one small trap hiding in the details here that I need to point out. When using the -ne operator this way, it's easy to mistakenly look at the logic backwards. This may look like a clever trick, but we have operators -contains and -in that handle this more efficiently.
And -notcontains does what you expect. The -contains operator checks the collection for your value. This is the preferred way to see if a collection contains your value. Using Where-Object or -eq walks the entire list every time and is significantly slower. The -in operator is just like the -contains operator except the collection is on the right-hand side.
Most of the operators we talked about do have a variation where you do not need to use the -not operator. But there are still times it is useful. You may see! I prefer to type it out because I find it hard to see when quickly looking at my scripts. You can combine expressions with the -and operator.
I added extra parentheses to make it clearer in that example but they're optional as long as the expression is simple. Here is the same example without them. Evaluation happens from left to right.
This is handy when you need to make sure a value exists before you use it. Just like with the -and operator, the evaluation happens from left to right. Also make note of how the syntax works for these operators. You need two separate expressions.
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