Environment.GetEnvironmentVariable Méthode
Définition
Important
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Extrait la valeur d'une variable d'environnement.
Surcharges
GetEnvironmentVariable(String) |
Récupère la valeur d'une variable d'environnement du processus en cours. |
GetEnvironmentVariable(String, EnvironmentVariableTarget) |
Récupère la valeur d'une variable d'environnement du processus en cours ou de la clé de Registre du système d'exploitation Windows pour l'utilisateur ou l'ordinateur local actuel. |
GetEnvironmentVariable(String)
- Source:
- Environment.cs
- Source:
- Environment.cs
- Source:
- Environment.cs
Récupère la valeur d'une variable d'environnement du processus en cours.
public:
static System::String ^ GetEnvironmentVariable(System::String ^ variable);
public static string GetEnvironmentVariable (string variable);
public static string? GetEnvironmentVariable (string variable);
static member GetEnvironmentVariable : string -> string
Public Shared Function GetEnvironmentVariable (variable As String) As String
Paramètres
- variable
- String
Nom de la variable d’environnement.
Retours
La valeur de la variable d'environnement spécifiée par variable
, ou null
si la variable d'environnement n'est pas trouvée.
Exceptions
variable
a la valeur null
.
L’appelant n’a pas l’autorisation nécessaire pour effectuer cette opération.
Exemples
L’exemple suivant utilise la GetEnvironmentVariable méthode pour récupérer la windir
variable d’environnement, qui contient le chemin d’accès du répertoire Windows.
using namespace System;
using namespace System::IO;
void main()
{
if (Environment::OSVersion->Platform == PlatformID::Win32NT)
{
// Change the directory to %WINDIR%
Environment::CurrentDirectory = Environment::GetEnvironmentVariable( "windir" );
DirectoryInfo^ info = gcnew DirectoryInfo( "." );
Console::WriteLine("Directory Info: {0}", info->FullName);
}
else
{
Console::WriteLine("This example runs on Windows only.");
}
}
// The example displays output like the following on a .NET implementation running on Windows:
// Directory Info: C:\windows
// The example displays the following output on a .NET implementation on Unix-based systems:
// This example runs on Windows only.
using System;
using System.IO;
public class Example
{
public static void Main()
{
if (Environment.OSVersion.Platform == PlatformID.Win32NT)
{
// Change the directory to %WINDIR%
Environment.CurrentDirectory = Environment.GetEnvironmentVariable("windir");
DirectoryInfo info = new DirectoryInfo(".");
Console.WriteLine("Directory Info: " + info.FullName);
}
else
{
Console.WriteLine("This example runs on Windows only.");
}
}
}
// The example displays output like the following on a .NET implementation running on Windows:
// Directory Info: C:\windows
// The example displays the following output on a .NET implementation on Unix-based systems:
// This example runs on Windows only.
open System
open System.IO
if Environment.OSVersion.Platform = PlatformID.Win32NT then
// Change the directory to %WINDIR%
Environment.CurrentDirectory <- Environment.GetEnvironmentVariable "windir"
let info = DirectoryInfo "."
printfn $"Directory Info: {info.FullName}"
else
printfn "This example runs on Windows only."
// The example displays output like the following on a .NET implementation running on Windows:
// Directory Info: C:\windows
// The example displays the following output on a .NET implementation on Unix-based systems:
// This example runs on Windows only.
Imports System.IO
Module Example
Public Sub Main()
If Environment.OSVersion.Platform = PlatformID.Win32NT Then
' Change the directory to %WINDIR%
Environment.CurrentDirectory = Environment.GetEnvironmentVariable("windir")
Dim info As New DirectoryInfo(".")
Console.WriteLine("Directory Info: " + info.FullName)
Else
Console.WriteLine("This example runs on Windows only.")
End If
End Sub
End Module
' The example displays output like the following on a .NET implementation running on Windows:
' Directory Info: C:\windows
' The example displays the following output on a .NET implementation on Unix-based systems:
' This example runs on Windows only.
L’exemple suivant tente de récupérer la valeur d’une variable d’environnement nommée Test1
à partir du bloc d’environnement de processus. Si la variable n’existe pas, l’exemple la crée et récupère sa valeur. L’exemple montre comment afficher la valeur de la variable. Si l’exemple a créé la variable, il appelle également la GetEnvironmentVariables(EnvironmentVariableTarget) méthode avec chaque membre de l’énumération EnvironmentVariableTarget pour établir que la variable peut être récupérée uniquement à partir du bloc d’environnement de processus actuel. Enfin, si l’exemple a créé la variable, il la supprime.
using System;
public class Example
{
public static void Main()
{
string value;
bool toDelete = false;
// Check whether the environment variable exists.
value = Environment.GetEnvironmentVariable("Test1");
// If necessary, create it.
if (value == null)
{
Environment.SetEnvironmentVariable("Test1", "Value1");
toDelete = true;
// Now retrieve it.
value = Environment.GetEnvironmentVariable("Test1");
}
// Display the value.
Console.WriteLine($"Test1: {value}\n");
// Confirm that the value can only be retrieved from the process
// environment block if running on a Windows system.
if (Environment.OSVersion.Platform == PlatformID.Win32NT)
{
Console.WriteLine("Attempting to retrieve Test1 from:");
foreach (EnvironmentVariableTarget enumValue in
Enum.GetValues(typeof(EnvironmentVariableTarget))) {
value = Environment.GetEnvironmentVariable("Test1", enumValue);
Console.WriteLine($" {enumValue}: {(value != null ? "found" : "not found")}");
}
Console.WriteLine();
}
// If we've created it, now delete it.
if (toDelete) {
Environment.SetEnvironmentVariable("Test1", null);
// Confirm the deletion.
if (Environment.GetEnvironmentVariable("Test1") == null)
Console.WriteLine("Test1 has been deleted.");
}
}
}
// The example displays the following output if run on a Windows system:
// Test1: Value1
//
// Attempting to retrieve Test1 from:
// Process: found
// User: not found
// Machine: not found
//
// Test1 has been deleted.
//
// The example displays the following output if run on a Unix-based system:
// Test1: Value1
//
// Test1 has been deleted.
module Example
open System
let mutable toDelete = false
// Check whether the environment variable exists.
let value =
let v = Environment.GetEnvironmentVariable "Test1"
// If necessary, create it.
if isNull v then
Environment.SetEnvironmentVariable("Test1", "Value1")
toDelete <- true
Environment.GetEnvironmentVariable "Test1"
else
v
// Display the value.
printfn $"Test1: {value}\n"
// Confirm that the value can only be retrieved from the process
// environment block if running on a Windows system.
if Environment.OSVersion.Platform = PlatformID.Win32NT then
printfn "Attempting to retrieve Test1 from:"
for enumValue in Enum.GetValues typeof<EnvironmentVariableTarget> do
let value = Environment.GetEnvironmentVariable("Test1", enumValue :?> EnvironmentVariableTarget)
printfn $""" {enumValue}: {if value <> null then "found" else "not found"}"""
printfn ""
// If we've created it, now delete it.
if toDelete then
Environment.SetEnvironmentVariable("Test1", null)
// Confirm the deletion.
if Environment.GetEnvironmentVariable "Test1" |> isNull then
printfn "Test1 has been deleted."
// The example displays the following output if run on a Windows system:
// Test1: Value1
//
// Attempting to retrieve Test1 from:
// Process: found
// User: not found
// Machine: not found
//
// Test1 has been deleted.
//
// The example displays the following output if run on a Unix-based system:
// Test1: Value1
//
// Test1 has been deleted.
Module Example
Public Sub Main()
Dim value As String
Dim toDelete As Boolean = False
' Check whether the environment variable exists.
value = Environment.GetEnvironmentVariable("Test1")
' If necessary, create it.
If value Is Nothing Then
Environment.SetEnvironmentVariable("Test1", "Value1")
toDelete = True
' Now retrieve it.
value = Environment.GetEnvironmentVariable("Test1")
End If
' Display the value.
Console.WriteLine($"Test1: {value}")
Console.WriteLine()
' Confirm that the value can only be retrieved from the process
' environment block if running on a Windows system.
If Environment.OSVersion.Platform = PlatformID.Win32NT Then
Console.WriteLine("Attempting to retrieve Test1 from:")
For Each enumValue As EnvironmentVariableTarget In
[Enum].GetValues(GetType(EnvironmentVariableTarget))
value = Environment.GetEnvironmentVariable("Test1", enumValue)
Console.WriteLine($" {enumValue}: {If(value IsNot Nothing, "found", "not found")}")
Next
Console.WriteLine()
End If
' If we've created it, now delete it.
If toDelete Then
Environment.SetEnvironmentVariable("Test1", Nothing)
' Confirm the deletion.
If Environment.GetEnvironmentVariable("Test1") = Nothing Then
Console.WriteLine("Test1 has been deleted.")
End If
End If
End Sub
End Module
' The example displays the following output if run on a Windows system:
' Test1: Value1
'
' Attempting to retrieve Test1 from:
' Process: found
' User: not found
' Machine: not found
'
' Test1 has been deleted.
'
' The example displays the following output if run on a Unix-based system:
' Test1: Value1
'
' Test1 has been deleted.
Remarques
Pour plus d’informations sur cette API, consultez Remarques supplémentaires sur l’API pour Environment.GetEnvironmentVariable.
Voir aussi
S’applique à
GetEnvironmentVariable(String, EnvironmentVariableTarget)
- Source:
- Environment.cs
- Source:
- Environment.cs
- Source:
- Environment.cs
Récupère la valeur d'une variable d'environnement du processus en cours ou de la clé de Registre du système d'exploitation Windows pour l'utilisateur ou l'ordinateur local actuel.
public:
static System::String ^ GetEnvironmentVariable(System::String ^ variable, EnvironmentVariableTarget target);
public static string? GetEnvironmentVariable (string variable, EnvironmentVariableTarget target);
public static string GetEnvironmentVariable (string variable, EnvironmentVariableTarget target);
static member GetEnvironmentVariable : string * EnvironmentVariableTarget -> string
Public Shared Function GetEnvironmentVariable (variable As String, target As EnvironmentVariableTarget) As String
Paramètres
- variable
- String
Nom d'une variable d'environnement.
- target
- EnvironmentVariableTarget
Une des valeurs de l'objet EnvironmentVariableTarget. Est pris en charge uniquement Process sur .NET s’exécutant sur des systèmes de type Unix.
Retours
La valeur de la variable d'environnement spécifiée par les paramètres variable
et target
, ou null
si la variable d'environnement n'est pas trouvée.
Exceptions
variable
a la valeur null
.
target
n’est pas une valeur de EnvironmentVariableTarget valide.
L’appelant n’a pas l’autorisation nécessaire pour effectuer cette opération.
Exemples
L’exemple suivant crée des variables d’environnement pour les EnvironmentVariableTarget.Processcibles , EnvironmentVariableTarget.Useret Machine , vérifie si le registre du système d’exploitation contient les variables d’environnement utilisateur et machine, puis supprime les variables d’environnement. Étant donné que .NET sur les systèmes de type Unix ne prend pas en charge les variables d’environnement par utilisateur et par machine, uniquement SetEnvironmentVariable(String, String) et SetEnvironmentVariable(String, String, EnvironmentVariableTarget) avec la valeur de EnvironmentVariableTarget.Process stocker correctement une variable d’environnement dans le bloc d’environnement de processus.
using System;
using System.Collections;
using Microsoft.Win32;
class Sample
{
public static void Main()
{
// Environment variable names for default, process, user, and machine targets.
string defaultEnvVar = nameof(defaultEnvVar);
string processEnvVar = nameof(processEnvVar);
string userEnvVar = nameof(userEnvVar);
string machineEnvVar = nameof(machineEnvVar);
string dft = nameof(dft);
string process = nameof(process);
string user = nameof(user);
string machine = nameof(machine);
// Set the environment variable for each target.
Console.WriteLine("Setting environment variables for each target...\n");
// The default target (the current process).
Environment.SetEnvironmentVariable(defaultEnvVar, dft);
// The current process.
Environment.SetEnvironmentVariable(processEnvVar, process,
EnvironmentVariableTarget.Process);
// The current user.
Environment.SetEnvironmentVariable(userEnvVar, user,
EnvironmentVariableTarget.User);
// The local machine.
Environment.SetEnvironmentVariable(machineEnvVar, machine,
EnvironmentVariableTarget.Machine);
// Define an array of environment variables.
string[] envVars = { defaultEnvVar,processEnvVar, userEnvVar, machineEnvVar };
// Try to get the environment variables from each target.
// The default (no specified target).
Console.WriteLine("Retrieving environment variables from the default target:");
foreach (var envVar in envVars)
{
var value = Environment.GetEnvironmentVariable(envVar) ?? "(none)";
Console.WriteLine($" {envVar}: {value}");
}
// The process block.
Console.WriteLine("\nRetrieving environment variables from the Process target:");
foreach (var envVar in envVars)
{
var value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.Process) ?? "(none)";
Console.WriteLine($" {envVar}: {value}");
}
// The user block.
Console.WriteLine("\nRetrieving environment variables from the User target:");
foreach (var envVar in envVars)
{
var value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.User) ?? "(none)";
Console.WriteLine($" {envVar}: {value}");
}
// The machine block.
Console.WriteLine("\nRetrieving environment variables from the Machine target:");
foreach (var envVar in envVars)
{
var value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.Machine) ?? "(none)";
Console.WriteLine($" {envVar}: {value}");
}
// Delete the environment variable for each target.
Console.WriteLine("\nDeleting environment variables for each target...\n");
// The default target (the current process).
Environment.SetEnvironmentVariable(defaultEnvVar, null);
// The current process.
Environment.SetEnvironmentVariable(processEnvVar, null,
EnvironmentVariableTarget.Process);
// The current user.
Environment.SetEnvironmentVariable(userEnvVar, null,
EnvironmentVariableTarget.User);
// The local machine.
Environment.SetEnvironmentVariable(machineEnvVar, null,
EnvironmentVariableTarget.Machine);
}
}
// The example displays the following output if run on a Windows system:
// Setting environment variables for each target...
//
// Retrieving environment variables from the default target:
// defaultEnvVar: dft
// processEnvVar: process
// userEnvVar: user
// machineEnvVar: (none)
//
// Retrieving environment variables from the Process target:
// defaultEnvVar: dft
// processEnvVar: process
// userEnvVar: user
// machineEnvVar: (none)
//
// Retrieving environment variables from the User target:
// defaultEnvVar: (none)
// processEnvVar: (none)
// userEnvVar: user
// machineEnvVar: (none)
//
// Retrieving environment variables from the Machine target:
// defaultEnvVar: (none)
// processEnvVar: (none)
// userEnvVar: (none)
// machineEnvVar: machine
//
// Deleting environment variables for each target...
//
// The example displays the following output if run on a Unix-based system:
//
// Setting environment variables for each target...
//
// Retrieving environment variables from the default target:
// defaultEnvVar: dft
// processEnvVar: process
// userEnvVar: (none)
// machineEnvVar: (none)
//
// Retrieving environment variables from the Process target:
// defaultEnvVar: dft
// processEnvVar: process
// userEnvVar: (none)
// machineEnvVar: (none)
//
// Retrieving environment variables from the User target:
// defaultEnvVar: (none)
// processEnvVar: (none)
// userEnvVar: (none)
// machineEnvVar: (none)
//
// Retrieving environment variables from the Machine target:
// defaultEnvVar: (none)
// processEnvVar: (none)
// userEnvVar: (none)
// machineEnvVar: (none)
//
// Deleting environment variables for each target...
module Sample
open System
// Environment variable names for default, process, user, and machine targets.
let rec defaultEnvVar = nameof defaultEnvVar
let rec processEnvVar = nameof processEnvVar
let rec userEnvVar = nameof userEnvVar
let rec machineEnvVar = nameof machineEnvVar
let rec dft = nameof dft
let rec proc = nameof proc
let rec user = nameof user
let rec machine = nameof machine
// Set the environment variable for each target.
printfn "Setting environment variables for each target...\n"
// The default target (the current process).
Environment.SetEnvironmentVariable(defaultEnvVar, dft)
// The current process.
Environment.SetEnvironmentVariable(processEnvVar, proc, EnvironmentVariableTarget.Process)
// The current user.
Environment.SetEnvironmentVariable(userEnvVar, user, EnvironmentVariableTarget.User)
// The local machine.
Environment.SetEnvironmentVariable(machineEnvVar, machine, EnvironmentVariableTarget.Machine)
// Define a list of environment variables.
let envVars = [ defaultEnvVar; processEnvVar; userEnvVar; machineEnvVar ]
// Try to get the environment variables from each target.
// The default (no specified target).
printfn "Retrieving environment variables from the default target:"
for envVar in envVars do
let value =
match Environment.GetEnvironmentVariable envVar with
| null -> "(none)"
| v -> v
printfn $" {envVar}: {value}"
// The process block.
printfn "\nRetrieving environment variables from the Process target:"
for envVar in envVars do
let value =
match Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.Process) with
| null -> "(none)"
| v -> v
printfn $" {envVar}: {value}"
// The user block.
printfn "\nRetrieving environment variables from the User target:"
for envVar in envVars do
let value =
match Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.User) with
| null -> "(none)"
| v -> v
printfn $" {envVar}: {value}"
// The machine block.
printfn "\nRetrieving environment variables from the Machine target:"
for envVar in envVars do
let value =
match Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.Machine) with
| null -> "(none)"
| v -> v
printfn $" {envVar}: {value}"
// Delete the environment variable for each target.
printfn "\nDeleting environment variables for each target...\n"
// The default target (the current process).
Environment.SetEnvironmentVariable(defaultEnvVar, null)
// The current process.
Environment.SetEnvironmentVariable(processEnvVar, null, EnvironmentVariableTarget.Process)
// The current user.
Environment.SetEnvironmentVariable(userEnvVar, null, EnvironmentVariableTarget.User)
// The local machine.
Environment.SetEnvironmentVariable(machineEnvVar, null, EnvironmentVariableTarget.Machine)
// The example displays the following output if run on a Windows system:
// Setting environment variables for each target...
//
// Retrieving environment variables from the default target:
// defaultEnvVar: dft
// processEnvVar: process
// userEnvVar: user
// machineEnvVar: (none)
//
// Retrieving environment variables from the Process target:
// defaultEnvVar: dft
// processEnvVar: process
// userEnvVar: user
// machineEnvVar: (none)
//
// Retrieving environment variables from the User target:
// defaultEnvVar: (none)
// processEnvVar: (none)
// userEnvVar: user
// machineEnvVar: (none)
//
// Retrieving environment variables from the Machine target:
// defaultEnvVar: (none)
// processEnvVar: (none)
// userEnvVar: (none)
// machineEnvVar: machine
//
// Deleting environment variables for each target...
//
// The example displays the following output if run on a Unix-based system:
//
// Setting environment variables for each target...
//
// Retrieving environment variables from the default target:
// defaultEnvVar: dft
// processEnvVar: process
// userEnvVar: (none)
// machineEnvVar: (none)
//
// Retrieving environment variables from the Process target:
// defaultEnvVar: dft
// processEnvVar: process
// userEnvVar: (none)
// machineEnvVar: (none)
//
// Retrieving environment variables from the User target:
// defaultEnvVar: (none)
// processEnvVar: (none)
// userEnvVar: (none)
// machineEnvVar: (none)
//
// Retrieving environment variables from the Machine target:
// defaultEnvVar: (none)
// processEnvVar: (none)
// userEnvVar: (none)
// machineEnvVar: (none)
//
// Deleting environment variables for each target...
Imports System.Collections
Imports Microsoft.Win32
Module Sample
Public Sub Main()
' Environment variable names for default, process, user, and machine targets.
Dim defaultEnvVar As String = NameOf(defaultEnvVar)
Dim processEnvVar As String = NameOf(processEnvVar)
Dim userEnvVar As String = NameOf(userEnvVar)
Dim machineEnvVar As String = NameOf(machineEnvVar)
Dim dft As String = NameOf(dft)
Dim process As String = NameOf(process)
Dim user As String = NameOf(user)
Dim machine As String = NameOf(machine)
' Set the environment variable for each target.
Console.WriteLine("Setting environment variables for each target...")
' The default target (the current process).
Environment.SetEnvironmentVariable(defaultEnvVar, dft)
' The current process.
Environment.SetEnvironmentVariable(processEnvVar, process,
EnvironmentVariableTarget.Process)
' The current user.
Environment.SetEnvironmentVariable(userEnvVar, user,
EnvironmentVariableTarget.User)
' The local machine.
Environment.SetEnvironmentVariable(machineEnvVar, machine,
EnvironmentVariableTarget.Machine)
Console.WriteLine()
' Define an array of environment variables.
Dim envVars As String() = { defaultEnvVar, processEnvVar, userEnvVar, machineEnvVar }
' Try to get the environment variables from each target.
' The default (no specified target).
Console.WriteLine("Retrieving environment variables from the default target:")
For Each envVar in envVars
Dim value = Environment.GetEnvironmentVariable(envVar)
Console.WriteLine($" {envVar}: {If(value IsNot Nothing, value, "(none)")}")
Next
Console.WriteLine()
' The process block.
Console.WriteLine("Retrieving environment variables from the Process target:")
For Each envVar in envVars
Dim value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.Process)
Console.WriteLine($" {envVar}: {If(value IsNot Nothing, value, "(none)")}")
Next
Console.WriteLine()
' The user block.
Console.WriteLine("Retrieving environment variables from the User target:")
For Each envVar in envVars
Dim value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.User)
Console.WriteLine($" {envVar}: {value}")
Next
Console.WriteLine()
' The machine block.
Console.WriteLine("Retrieving environment variables from the Machine target:")
For Each envVar in envVars
Dim value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.Machine)
Console.WriteLine($" {envVar}: {value}")
Next
Console.WriteLine()
' Delete the environment variable for each target.
Console.WriteLine("Deleting environment variables for each target...")
' The default target (the current process).
Environment.SetEnvironmentVariable(defaultEnvVar, Nothing)
' The current process.
Environment.SetEnvironmentVariable(processEnvVar, Nothing,
EnvironmentVariableTarget.Process)
' The current user.
Environment.SetEnvironmentVariable(userEnvVar, Nothing,
EnvironmentVariableTarget.User)
' The local machine.
Environment.SetEnvironmentVariable(machineEnvVar, Nothing,
EnvironmentVariableTarget.Machine)
End Sub
End Module
' The example displays the following output if run on a Windows system:
' Setting environment variables for each target...
'
' Retrieving environment variables from the default target:
' defaultEnvVar: dft
' processEnvVar: process
' userEnvVar: user
' machineEnvVar: (none)
'
' Retrieving environment variables from the Process target:
' defaultEnvVar: dft
' processEnvVar: process
' userEnvVar: user
' machineEnvVar: (none)
'
' Retrieving environment variables from the User target:
' defaultEnvVar: (none)
' processEnvVar: (none)
' userEnvVar: user
' machineEnvVar: (none)
'
' Retrieving environment variables from the Machine target:
' defaultEnvVar: (none)
' processEnvVar: (none)
' userEnvVar: (none)
' machineEnvVar: machine
'
' Deleting environment variables for each target...
'
' The example displays the following output if run on a Unix-based system:
'
' Setting environment variables for each target...
'
' Retrieving environment variables from the default target:
' defaultEnvVar: dft
' processEnvVar: process
' userEnvVar: (none)
' machineEnvVar: (none)
'
' Retrieving environment variables from the Process target:
' defaultEnvVar: dft
' processEnvVar: process
' userEnvVar: (none)
' machineEnvVar: (none)
'
' Retrieving environment variables from the User target:
' defaultEnvVar: (none)
' processEnvVar: (none)
' userEnvVar: (none)
' machineEnvVar: (none)
'
' Retrieving environment variables from the Machine target:
' defaultEnvVar: (none)
' processEnvVar: (none)
' userEnvVar: (none)
' machineEnvVar: (none)
'
' Deleting environment variables for each target...
Remarques
Pour plus d’informations sur cette API, consultez Remarques supplémentaires sur l’API pour Environment.GetEnvironmentVariable.
Voir aussi
- SetEnvironmentVariable(String, String, EnvironmentVariableTarget)
- GetEnvironmentVariables()
- EnvironmentVariableTarget