Skip to main content

When to use Single and Double quotes with PowerShell

By

Here is another one of those enduring questions from my PowerShell classes. When to use single and double quotes.

First off we need to establish the object type that is created by both single and double quotes. Take a look at the code below. Both single and double quotes produce a System.String object type. At this point there is no difference between the two.

PS C:\> $Single = ''

 

PS C:\> $Double = ""

 

PS C:\> $Single.GetType()

 

IsPublic IsSerial Name                                     BaseType                                         

-------- -------- ----                                     --------                                         

True     True     String                                   System.Object                                    

 

 

 

PS C:\> $Double.GetType()

 

IsPublic IsSerial Name                                     BaseType                                         

-------- -------- ----                                     --------                                         

True     True     String                                   System.Object 

The difference comes when you create strings that contain variables.

PS C:\> $Var1 = "Hello"

 

PS C:\> $Var2 = 'World'

 

PS C:\> Write-Output "$Var1 $Var2"

Hello World

 

PS C:\> Write-Output '$Var1 $Var2'

$Var1 $Var2

Here two strings are produce from variables. The first utilizes double quotes while the second utilizes single quotes. In the first, the value of the variables are placed in the string. In the second string, utilizing single quotes, the characters are treated as literal. In other words, they are no longer treated as variable names.

You may be thinking “Big deal”. Well, here is where it can become a big deal. Consider the following.

PS C:\> Write-Output 'The price of gas is $4.35 a gallon.'

The price of gas is $4.35 a gallon.

 

PS C:\> Write-Output "The price of gas is $4.35 a gallon."

The price of gas is .35 a gallon.

Do you see the difference? In the string created with single quotes, you get accurate output. In the other string, PowerShell is looking for the value of the variable $4. Well, $4 has a value of NULL. Now you just set the price of gas at $.35 a gallon. We call this a RGE. Otherwise known as a Resume Generating Event.

You could write your string this way.

PS C:\> Write-Output "The price of gas is `$4.35 a gallon."

The price of gas is $4.35 a gallon.

What you may not see is in front of the “$” is a “`” back tick. This is the PowerShell Escape Character. Be careful if you use it. It is hard to see. The Escape Character makes the dollar sign be treated as a character instead of the name of a variable. This will give us the correct output. Remember, this is not the single quote, but the back tick.  The back tick is on the left of a US keyboard where the single quote is on the right.

Labels:

Comments

Post a Comment

Popular posts from this blog

How to list all the AD LDS instances on a server

By
AD LDS allows you to provide directory services to applications that are free of the confines of Active Directory.  To list all the AD LDS instances on a server, follow this procedure: Log into the server in question Open a command prompt. Type dsdbutil and press Enter Type List Instances and press Enter . You will receive a list of the instance name, both the LDAP and SSL port numbers, the location of the database, and its status.
Post a Comment
Read more

How to run GPResult on a remote client with PowerShell

By
In the past, to run the GPResult command, you would need to either physically visit this client, have the user do it, or use and RDP connection.  In all cases, this will disrupt the user.  First, you need PowerShell remoting enabled on the target machine.  You can do this via Group Policy . Open PowerShell and type this command. Invoke-Command –ScriptBlock {GPResult /r} –ComputerName <ComputerName> Replace <ComputerName> with the name of the target.  Remember, the target needs to be online and accessible to you.
Post a Comment
Read more

Error icon when creating a GPO Preference drive map

By
You may not have an error at all.  Take a look at the drive mapping below. The red triangle is what threw us off.  It is not an error.  It is simply a color representation of the Replace option of the Action field in the properties of the drive mappings. Create action This give you a green triangle. The Create action creates a new mapped drive for users. Replace Action The Replace action gives you a red triangle.  This action will delete and recreate mapped drives for users. The net result of the Replace action is to overwrite all existing settings associated with the mapped drive. If the drive mapping does not exist, then the Replace action creates a new drive mapping. Update Action The Update action will have a yellow triangle. Update will modify settings of an existing mapped drive for users. This action differs from Replace in that it only updates settings defined within the preference item. All other settings remain as configured on the ma...
1 comment
Read more