Add user environment variable windows 10

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Add user environment variable windows 10

Environment variables are not often seen directly when using Windows. However there are cases, especially when using the command line, that setting and updating environment variables is a necessity. In this series we talk about the various approaches we can take to set them. In this article we look at how to interface with environment variables using the Command Prompt and Windows PowerShell. We also note where in the registry the environment variables are set, if you needed to access them in such a fashion. Print environment variables You can use environment variables in the values of other environment variables. It is then helpful to be able to see what environment variables are set already. This is how you do it: Command Prompt List all environment variables Command Prompt - C:\> Print a particular environment variable: Command Prompt - C:\> Windows PowerShell List all environment variables Windows PowerShell - PS C:\> Print a particular environment variable: Windows PowerShell - PS C:\> Set Environment Variables To set persistent environment variables at the command line, we will use setx.exe. It became part of Windows as of Vista/Windows Server 2008. Prior to that, it was part of the Windows Resource Kit. If you need the Windows Resource Kit, see Resources at the bottom of the page. setx.exe does not set the environment variable in the current command prompt, but it will be available in subsequent command prompts. User Variables Command Prompt - C:\> 1setx EC2_CERT "%USERPROFILE%\aws\cert.pem" Open a new command prompt. Command Prompt - C:\> System Variables To edit the system variables, you'll need an administrative command prompt. See HowTo: Open an Administrator Command Prompt in Windows to see how. Command Prompt - C:\> 1setx EC2_HOME "%APPDATA%\aws\ec2-api-tools" /M Registry Warning This method is recommended for experienced users only. The location of the user variables in the registry is: HKEY_CURRENT_USER\Environment. The location of the system variables in the registry is: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment. When setting environment variables through the registry, they will not recognized immediately. One option is to log out and back in again. However, we can avoid logging out if we send a WM_SETTINGCHANGE message, which is just another line when doing this programatically, however if doing this on the command line it is not as straightforward. One way is to get this message issued is to open the environment variables in the GUI, like we do in HowTo: Set an Environment Variable in Windows - GUI; we do not need to change anything, just open the Environment Variables window where we can see the environment variables, then hit OK. Another way to get the message issued is to use setx, this allows everything to be done on the command line, however requires setting at least one environment variable with setx. Printing Environment Variables With Windows XP, the reg tool allows for accessing the registry from the command line. We can use this to look at the environment variables. This will work the same way in the command prompt or in powershell. This technique will also show the unexpanded environment variables, unlike the approaches shown for the command prompt and for powershell. First we'll show the user variables: Command Prompt - C:\> 1reg query HKEY_CURRENT_USER\Environment We can show a specific environment variable by adding /v then the name, in this case we'll do TEMP: Command Prompt - C:\> 1reg query HKEY_CURRENT_USER\Environment /v TEMP Now we'll list the system environment variables: Command Prompt - C:\> 1reg query "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" And same as with the user variables we can query a specific variable. Command Prompt - C:\> 1reg query "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v PATH Unsetting a Variable When setting environment variables on the command line, setx should be used because then the environment variables will be propagated appropriately. However one notable thing setx doesn't do is unset environment variables. The reg tool can take care of that, however another setx command should be run afterwards to propagate the environment variables. The layout for deleting a user variable is: reg delete HKEY_CURRENT_USER\Environment /v variable_name /f. If /f had been left off, we would have been prompted: Delete the registry value EXAMPLE (Yes/No)?. For this example we'll delete the user variable USER_EXAMPLE: Command Prompt - C:\> 1reg delete HKEY_CURRENT_USER\Environment /v USER_EXAMPLE /f Deleting a system variable requires administrator privileges. See HowTo: Open an Administrator Command Prompt in Windows to see how to do this. The layout for deleting a system variable is: reg delete "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v variable_name /f. For this example we'll delete the system variable SYSTEM_EXAMPLE: Command Prompt - C:\> 1reg delete "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v SYSTEM_EXAMPLE /f If this was run as a normal user you'll get: But run in an administrator shell will give us: Finally we'll have to run a setx command to propagate the environment variables. If there were other variables to set, we could just do that now. However if we were just interested in unsetting variables, we will need to have one variable left behind. In this case we'll set a user variable named throwaway with a value of trash Command Prompt - C:\> Resources Windows Server 2003 Resource Kit Tools will also work with Windows XP and Windows XP SP1; use Windows XP Service Pack 2 Support Tools with Windows XP SP2. Neither download is supported on 64-bit version. Parts in this series Using PowerShell to set Windows environment variables, read environment variables and create new environment variables is easy once you know the trick. The tricks you learn in this article will work for Windows 10 environment variables as well as any Windows client/server after Windows 7 SP1/Windows Server 2008. PowerShell provides many different ways to interact with Windows environment variables from the $env: PSDrive. the registry, and the [System.Environment] .NET class. You'll learn about each method including understand environment variable scope in this step-by-step walkthrough. Assumptions Throughout this article, I'll be using Windows PowerShell 5.1 on Windows 10. But if you have any version of Windows PowerShell later than v3 on Windows 7 SP1 or later, the techniques I'm about to show you should work just fine. What are Environment Variables? Environment variables, as the name suggests, store information about the environment that is used by Windows and applications. Environment variables can be accessed by graphical applications such as Windows Explorer and plain text editors like Notepad, as well as the cmd.exe and PowerShell. Using environment variables helps you to avoid hard-coding file paths, user or computer names and much more in your PowerShell scripts or modules. Common Environment Variables As you begin to learn more about how to work with environment variables in PowerShell, you'll come across many different variables. Some are more useful than others. Below is a list of some of the common environment variables and their usage for reference. VariableUsageClientNameThe name of the remote computer connected via a Remote Desktop session.SessionNameThis helps to identify if the current Windows session is regarded by the operating system as running at the console. For console sessions SessionName will be `Console'. Enhanced Session connections to Hyper-V Virtual Machines do not report SessionName as `Console', whereas Standard Sessions puterNameThe name of the computer.SystemRoot and WindirThe path to the current Windows installation.ProgramFiles and ProgramFiles(x86)The default locations for x64 and x86 programs.ProgramW6432The default location for programs, avoiding 32/64 bit redirection. This variable only applies for 32 bit processes running on a 64 bit platform. This means that you can use it to identify when a 32 bit instance of PowerShell is running on a 64 bit system.UserDNSDomainThe Fully Qualified Domain Name of the Active Directory domain that the current user logged on to. Only present for domain logons.UserDomainThe NETBIOS-style name of the domain that the current user logged on to. Can be a computer name if there's no domain.UserDomainRoamingProfileThe location of the central copy of the roaming profile for the user, if any. Only present for domain logons.UserNameThe name of the currently logged on user.UserProfileThe location of the profile of the current user on the local computer. Environment Variable Scopes There are three scopes of environment variables. Think of scopes as layers of variables that build up to give a total picture. Combined, these "layers" provide many different environment variables to any running process in Windows. Environment Variable Scope "Hierarchy" Each of these "layers" either combine or overwrite one another. They are defined in a hierarchy like: machine ?> user ?> process with each scoped variable overwriting the parent variable if one exists in the parent scope. For example, a common environment variable is TEMP. This variable stores the folder path to Windows' local temporary folder. This environment variable is set to: C:\WINDOWS\TEMP in the machine scopeC:\Users\\AppData\Local\Temp in the user scopeC:\Users\\AppData\Local\Temp in the process scope. If there's no TEMP environment variable set in the user scope then the end result will be C:\WINDOWS\TEMP. Environment Variable Scope Types There are three different environment variable scopes in Windows. Machine Environment variables in the machine scope are associated with the running instance of Windows. Any user account can read these, but setting, changing or deleting them needs to done with elevated privileges. User Environment variables in the user scope are associated with the user running the current process. User variables overwrite machine-scoped variables having the same name. Note: Microsoft recommends that Machine and User scoped environment variable values contain no more than 2048 characters. Process Environment variables in the process scope are a combination of the machine and user scopes, along with some variables that Windows creates dynamically. Below is a list of environment variables available to a running process. All of these variables are dynamically created. ALLUSERSPROFILEAPPDATACOMPUTERNAMEHOMEDRIVEHOMEPATHLOCALAPPDATALOGONSERVERPROMPTPUBLICSESSIONSystemDriveSystemRootUSERDNSDOMAINUSERDOMAINUSERDOMAIN_ROAMINGPROFILEUSERNAMEUSERPROFILE Environment Variables in the Registry Environment variables are stored in two registry locations, one for the user scope and one for the machine scope. Don't Use the Registry to Manage Environment Variables There's a catch when making changes to variables inside of the registry. Any running processes will not see variable changes in the registry. Processes only see the registry variables and values that were present when the process was started, unless Windows notifies them that there has been a change. Instead of modifying the registry directly, you can use a .NET class instead. The .NET [System.Environment] class can modify machine and user?scoped environment variables and handle the registry housekeeping for you. Modifying environment variables in the registry directly, whilst possible, doesn't make sense. The .NET class offers a simpler, Microsoft-supported approach. You'll learn about using the [System.Environment] .NET class later in this article. Environment Variable Registry Locations and Querying I hope you've been convinced to not modify the registry directly but if you'd like to take a peek at what's in there, you can find all user environment variables in the HKEY_CURRENT_USER\Environment key. Machine-scoped environment variables are stored at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment. Inside of either of these keys lies registry values of type REG_SZ or REG_EXPAND_SZ. REG_EXPAND_SZ values hold environment variables embedded as part of their value. These environment variables are expanded when the value is retrieved. To demonstrate this, use the REG utility. This is a small command-line utility included with Windows. Query the TEMP environment variable as seen below. Run REG with the QUERY parameter to retrieve the value of the TEMP variable. > REG QUERY HKCU\Environment /V TEMP HKEY_CURRENT_USER\Environment TEMP REG_EXPAND_SZ %USERPROFILE%\AppData\Local\Temp You'll sometimes notice environment variables displayed surrounded by percentage symbols (%COMPUTERNAME%) like above. This is the old-school way of showing environment variables via cmd.exe and batch files. Know that PowerShell does not recognize this format. The REG utility allows us to see the native value of the registry value. The value type is REG_EXPAND_SZ and the value contains the %USERPROFILE% environment variable. If you'd rather use PowerShell to retrieve the registry value, you can so using the Get-Item cmdlet as shown below. PS51> Get-ItemProperty -Path HKCU:\Environment -Name TEMP TEMP : C:\Users\\AppData\Local\Temp PSPath : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER\Environment PSParentPath : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER PSChildName : Environment PSDrive : HKCU PSProvider : Microsoft.PowerShell.Core\Registry View and Set Windows Environment Variables via the GUI To see a GUI view of the user and system environment variables, run SystemPropertiesAdvanced.exe from PowerShell, a command prompt or from Windows Key+R to display the System Properties Advanced tab. Click on the EnvironmentVariables button, which is highlighted in the image below. The System Properties dialog, Advanced tab The Environment Variables dialog, shown below, allows you to view, create and modify user and machine-scoped environment variables. Note that the dialog refers to machine scoped variables as System variables. The Environment Variables dialog Now that you have an understanding of environment variables, let's get to what you're here for, managing them with PowerShell! There are a few different ways you can interact with environment variables using PowerShell. The Env: PSDrive and Provider ? session-based. Only sets the values of environment variables for the current PowerShell session$env: variables ? sessionbased. Only sets the values of environment variables for the current PowerShell sessionThe [System.Environment] .NET Class ? allows you to persist user and system-scoped environment variables across sessions and reboots The Env: PSDrive and Provider One of the best way to read environment variables is a PowerShell concept known as PowerShell drives (PS drives). A PS drive allows you to treat environment variables as if they are a file system through the Env: drive. Switching to the Env: Drive Like all PS drives, you reference it via paths like Env:\TEMP, Env:\COMPUTERNAME, etc. But to save some keystrokes, switch to the Env: drive just as you would any file system drive, as shown below. PS51> cd Env: PS51 Env:\> ## or PS51> Set-Location Env: PS Env:\> Tab-Completion with the Env: Drive You can use the same commands you would use to access a file system, such as Get-Item and Get-ChildItem to access environment variables. But instead of the file system, you're reading the Env: drive. Because environment variables are stored in a PS drive, you can use the tab completion feature of PowerShell to cycle through the available variables, as shown below. Env: tab completion ? finding environment variables starting with the letter C Let's now jump into a couple examples of how you can use the Env: PS drive to work with environment variables. Listing Environment Variables with Env: PS51> Get-Item -Path Env: PS51> Get-Item -Path Env:USERNAME Listing Environment Variables Using a Wildcard with Env: PS51> Get-Item -Path Env:user* Finding Environment Variable Values with Env: The results of these commands are key/value [System.Collections.DictionaryEntry] .NET objects. These objects hold the environment variable's name in the Name property and the value in the Value property. You can access a specific value of an environment variable by wrapping the Get-Item command reference in parentheses and referencing the Value property as shown below: PS51> (Get-Item -Path Env:computername).Value MYCOMPUTERHOSTNAME In situations where you need to only return certain environment variables, use standard PowerShell cmdlets such as Select-Object and Where-Object to select and filter the objects returned by the Env: provider. In the example below, only the environment variable COMPUTERNAME is returned. PS51> Get-ChildItem -Path Env: | Where-Object -Property Name -eq 'COMPUTERNAME' As an alternative method, use the Get-Content cmdlet. This cmdlet returns a [String] object containing the value of the environment variable. This object is simpler to deal with as it returns only the value, rather than an object with Name and Value properties. PS51> Get-Content -Path Env:\COMPUTERNAME Demo: Inserting Environment Values in a String Using Get-Content, you can find the value of an environment variable and insert the COMPUTERNAME environment variable, for example, into a text string. PS51> 'Computer Name is: {0}' -f (Get-Content -Path Env:COMPUTERNAME) Computer Name is: MYCOMPUTER Setting an Environment Variable (And Creating) with Env: Create new environment variables with PowerShell using the New-Item cmdlet. Provide the name of the environment variable in the form Env:\ for the Name value and the value of the environment variable for the Value parameter as shown below. PS51> New-Item -Path Env:\MYCOMPUTER -Value MY-WIN10-PC Name Value ---- ----- MYCOMPUTER MY-WIN10-PC Use the Setitem cmdlet to set an environment variable, or create a new one if it doesn't already exist. You can see below using the Set-Item cmdlet, you can both create or modify and environment variable. PS51> Set-Item -Path Env:testvariable -Value "Alpha" Sometimes the situation arises that you need to replicate the value of an environment variable. You can do this using the Copy-Item cmdlet. Below you can see that the value of the COMPUTERNAME variable is copied to MYCOMPUTER, overwriting its existing value. PS51> Get-Item -Path Env:\MYCOMPUTER Name Value ---- ----- MYCOMPUTER MY-WIN10-PC PS51> Copy-Item -Path Env:\COMPUTERNAME -Destination Env:\MYCOMPUTER PS51> Get-Item Path Env:\MYCOMPUTER Name Value ---- ----- MYCOMPUTER WIN10-1903 Removing an Environment Variable with Env: Situations will arise where an environment variable is no longer needed. You can remove environment variables using one of three methods: Use the Set-Item cmdlet to set an environment variable to an empty value PS51> Set-Item Path Env:\MYCOMPUTER -Value '' Use the Remove-Item cmdlet. PS51> Remove-Item -Path Env:\MYCOMPUTER Use the Clear-Item cmdlet. PS51> Clear-Item -Path Env:\MYCOMPUTER Renaming an Environment Variable with Env: In situations where the name of an environment variable needs to be changed, you have the option to rename, rather than delete and recreate with the Env: provider. Use the Rename-Item cmdlet to change the name of an environment variable whilst keeping its value. Below you can see that you can see that the MYCOMPUTER variable is renamed to OLDCOMPUTER whilst retaining its value. PS51> Rename-Item -Path Env:\MYCOMPUTER -NewName OLDCOMPUTER PS51> Get-Item -Path OLDCOMPUTER Name Value ---- ----- OLDCOMPUTER WIN10-1903 $Env: Variables Having mastered the Env: drive to treat environment variables as files, this section shows you how to treat them as variables. Another way you can manage in-session environment variables is using the the PowerShell Expression Parser. This feature allows you to use the $Env: scope to access environment variables. Getting an Environment Variable with $Env: Using the $Env scope, you can reference environment variables directly without using a command like Get-Item as shown below. PS51> $env:computername This method makes it easy to insert environment variables into strings like below: PS51> "The Computer Name is {0}" -f $env:computername The Computer Name is WIN10-1809 PS51> "The Computer Name is $env:computername" The Computer Name is WIN10-1809 Setting or Creating an Environment Variable with $Env: Setting an environment variable using this method is straightforward. This will also create a new environment variable if one does not already exist like below. PS51> $env:testvariable = "Alpha" Use the += syntax to add to an existing value, rather than overwriting it. PS51> $env:testvariable = "Alpha" PS51> $env:testvariable += ",Beta" PS51> $env:testvariable Alpha,Beta Removing an Environment Variable with $Env: To remove an environment variable using this method, simple set its value to an empty string. PS51> $env:testvariable = '' Using the [System.Environment] .NET Class The .NET class [System.Environment] offers methods for getting and setting environment variables also. This is only method to access various environment scopes directly and set environment variables that survive across PowerShell sessions. In all of the following examples, if no scope is provided, the process scope is assumed. When using the [System.Environment], you'll use a few different .NET static class methods. You don't need to understand what a static method is. You only need to understand to use any of the techniques you're about to learn, you'll need to first reference the class ([System.Environment]) followed by two colons (::) then followed by the method. Listing Environment Variables with [System.Environment] If you'd like to see all environment variables in a particular scope, you'd use the GetEnvironmentVariables method. This method returns all environment variables by the scope specified as the method argument (in parentheses). PS51> [System.Environment]::GetEnvironmentVariables('User') PS51> [System.Environment]::GetEnvironmentVariables('Machine') PS51> [System.Environment]::GetEnvironmentVariables('Process') # The same as Process PS51> [System.Environment]::GetEnvironmentVariables() Getting Single Environment Variables with [System.Environment] If you need to find a specific environment variable you can do so two different ways. GetEnvironmentVariables(). ? not recommendedGetEnvironmentVariable('','') GetEnvironmentVariables() Using the GetEnvironmentVariables() method, you use dot notation to reference the value. Enclose the [System.Environment] class and static method reference in parentheses followed by a dot then the name of the environment variable like below: PS51> ([System.Environment]::GetEnvironmentVariables()).APPDATA Note that when referencing environment variables this way, you must ensure you match capitalization! In the example above, try to reference the APPDATA variable using appdata. Use the GetEnvironmentVariable() instead. GetEnvironmentVariable() Rather than using the GetEnvironmentVariables() method, instead use GetEnvironmentVariable() to find single environment variables. It gets around the issue with capitalization and also allows you to specify the scope. To use this method, specify the environment variable name and the scope you'd like to look for that variable in separated by comma. PS51> [System.Environment]::GetEnvironmentVariable('ComputerName','User') # Blank PS51> [System.Environment]::GetEnvironmentVariable('ComputerName','Machine') # Blank PS51> [System.Environment]::GetEnvironmentVariable('ComputerName','Process') WIN10-1903 # The same as Process PS51> [System.Environment]::GetEnvironmentVariable('ComputerName') WIN10-1903 Setting an Environment Variable with [System.Environment] Use the SetEnvironmentVariable() method to set the value of an environment variable for the given scope, or create a new one if it does not already exist. When setting variables in the process scope, you'll find that the process scope is volatile while changes to the user and machine scopes are permanent. PS51> [System.Environment]::SetEnvironmentVariable('TestVariable','Alpha','User') PS51> [System.Environment]::SetEnvironmentVariable('TestVariable','Alpha','Process') PS51> [System.Environment]::SetEnvironmentVariable('TestVariable','Alpha','Machine') # The same as Process PS51> [System.Environment]::SetEnvironmentVariable('TestVariable','Alpha') Note: Calling the SetEnvironmentVariable method with a variable name or value of 32767 characters or more will cause an exception to be thrown. Removing an Environment Variable with [System.Environment] Use the SetEnvironmentVariable() method to remove an environment variable for the given scope by setting its value to an empty string. PS51> [System.Environment]::SetEnvironmentVariable('TestVariable', '', 'User') PS51> [System.Environment]::SetEnvironmentVariable('TestVariable', '', 'Process') PS51> [System.Environment]::SetEnvironmentVariable('TestVariable', '', 'Machine') # The same as process PS51> [System.Environment]::SetEnvironmentVariable('TestVariable', '') Useful PowerShell Environment Variables Like many other Windows applications, PowerShell has some environment variables of it's own. Two useful environment variables to know about are PSExecutionPolicyPreference and PSModulePath. PSExecutionPolicyPreference The PSExecutionPolicyPreference environment variable stores the current PowerShell execution policy. It is created if a session-specific PowerShell execution policy is set by: Running the Set-ExecutionPolicy cmdlet with a Scope parameter of ProcessRunning the powershell.exe executable to start a new session, using the ExecutionPolicy command line parameter to set a policy for the session. PSModulePath The PSModulePath environment variable contains the path that PowerShell searches for modules if you do not specify a full path. It is formed much like the standard PATH environment variable, with individual directory paths separated by a semicolon. PS51> $env:PSModulePath C:\Program Files\WindowsPowerShell\Modules;C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules Quick tip: Split each folder to get a string array to process each path individually using $env:PSModulePath.split(`;') Environment variables are a useful method for getting information about a running system, or storing information across sessions and reboots. Whether you're just reading the default Windows operating system environment variables and creating your own, you now can manage them using a variety of ways with PowerShell! Further Reading

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