EnvironmentVariableTarget EnvironmentVariableTarget EnvironmentVariableTarget EnvironmentVariableTarget Enum

Definice

Určuje umístění, kde je proměnná prostředí uložená nebo načtená v operaci set nebo Get.Specifies the location where an environment variable is stored or retrieved in a set or get operation.

public enum class EnvironmentVariableTarget
[System.Runtime.InteropServices.ComVisible(true)]
public enum EnvironmentVariableTarget
type EnvironmentVariableTarget = 
Public Enum EnvironmentVariableTarget
Dědičnost
EnvironmentVariableTargetEnvironmentVariableTargetEnvironmentVariableTargetEnvironmentVariableTarget
Atributy

Pole

Machine Machine Machine Machine 2

Proměnná prostředí se ukládá nebo načítá z HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Environment klíče v registru operačního systému Windows.The environment variable is stored or retrieved from the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Environment key in the Windows operating system registry. Tato hodnota by se měla používat jenom u implementací .NET, které běží jenom na systémech Windows.This value should be used on .NET implementations running on Windows systems only.

Process Process Process Process 0

Proměnná prostředí se ukládá nebo načítá z bloku prostředí přidruženého k aktuálnímu procesu.The environment variable is stored or retrieved from the environment block associated with the current process.

User User User User 1

Proměnná prostředí se ukládá nebo načítá z HKEY_CURRENT_USER\Environment klíče v registru operačního systému Windows.The environment variable is stored or retrieved from the HKEY_CURRENT_USER\Environment key in the Windows operating system registry. Tato hodnota by se měla používat jenom u implementací .NET, které běží jenom na systémech Windows.This value should be used on .NET implementations running on Windows systems only.

Příklady

Následující příklad používá EnvironmentVariableTarget výčet v metodách, které vytváří, načítají a odstraňují proměnné prostředí.The following example uses the EnvironmentVariableTarget enumeration in methods that create, retrieve, and delete environment variables. Výstup z příkladu ukazuje, že proměnné environmnent uložené a načtené bez určení EnvironmentVariableTarget hodnoty jsou uloženy v bloku prostředí přidruženém k aktuálnímu procesu (EnvironmentVariableTarget.Process).The output from the example shows that environmnent variables stored and retrieved without specifying a EnvironmentVariableTarget value are stored in the environment block associated with the current process (EnvironmentVariableTarget.Process). Ukázkový výstup z počítačů se systémem UNIX také ukazuje, že se pokusí definovat proměnnou prostředí s jinou hodnotou než EnvironmentVariableTarget.Process je ignorováno.The example output from Unix-based systems also shows that attempts to define an environment variable with a value other than EnvironmentVariableTarget.Process is ignored.

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...
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...

Poznámky

Výčet používá určité přetížení Environment.SetEnvironmentVariablemetod, Environment.GetEnvironmentVariablea Environment.GetEnvironmentVariables k určení umístění, nebo cíle, kde je uložen nebo načten název a hodnota proměnné prostředí. EnvironmentVariableTargetThe EnvironmentVariableTarget enumeration is used by certain overloads of the Environment.SetEnvironmentVariable, Environment.GetEnvironmentVariable, and Environment.GetEnvironmentVariables methods to specify the location, or target, where the name and value of an environment variable is stored or retrieved.

Cílem může být jedno ze tří umístění:The target can be one of three locations:

  • Blok prostředí přidružený k aktuálnímu procesu (EnvironmentVariableTarget.Process).The environment block associated with the current process (EnvironmentVariableTarget.Process).

    Uživatel vytvoří proměnnou prostředí v operaci set.The user creates the environment variable in a set operation. Po ukončení procesu operační systém zničí proměnnou prostředí v tomto procesu.When the process terminates, the operating system destroys the environment variable in that process.

  • Klíč registru operačního systému Windows rezervovaný pro proměnné prostředí přidružené k aktuálnímu uživateli (EnvironmentVariableTarget.User)The Windows operating system registry key reserved for environment variables associated with the current user (EnvironmentVariableTarget.User).

    Pokud uživatel v systémech Windows vytvoří proměnnou prostředí v operaci set, operační systém uloží proměnnou prostředí do systémového registru, ale ne v aktuálním procesu.On Windows systems, when the user creates the environment variable in a set operation, the operating system stores the environment variable in the system registry, but not in the current process. Pokud uživatel spustí nový proces, operační systém zkopíruje proměnnou prostředí z registru do tohoto procesu.If the user starts a new process, the operating system copies the environment variable from the registry to that process. Po ukončení procesu operační systém zničí proměnnou prostředí v tomto procesu.When the process terminates, the operating system destroys the environment variable in that process. Proměnná prostředí v registru ale přetrvá, dokud ji uživatel neodebere programově nebo prostřednictvím nástroje operačního systému.However, the environment variable in the registry persists until the user removes it programmatically or by means of an operating system tool.

    V systémech UNIX se pokus o vytvoření proměnné vyhledáte s EnvironmentVariable.User žádným účinkem neprojeví a pokus o načtení proměnné vyhledáte pomocí EnvironmentVariable.User funkce Returns null (in C#) nebo Nothing (v Visual Basic).On Unix-based systems, an attempt to create an enviroment variable with EnvironmentVariable.User has no effect, and an attempt to retrieve an enviroment variable using EnvironmentVariable.User returns null (in C#) or Nothing (in Visual Basic).

  • Klíč registru rezervovaný pro proměnné prostředí přidružené ke všem uživatelům v místním počítači (EnvironmentVariableTarget.Machine).The registry key reserved for environment variables associated with all users on the local machine (EnvironmentVariableTarget.Machine).

    Když uživatel vytvoří proměnnou prostředí v operaci set, operační systém uloží proměnnou prostředí do systémového registru, ale ne v aktuálním procesu.When a user creates the environment variable in a set operation, the operating system stores the environment variable in the system registry, but not in the current process. Pokud některý uživatel na místním počítači spustí nový proces, zkopíruje operační systém proměnnou prostředí z registru do tohoto procesu.If any user on the local machine starts a new process, the operating system copies the environment variable from the registry to that process. Po ukončení procesu operační systém zničí proměnnou prostředí v tomto procesu.When the process terminates, the operating system destroys the environment variable in that process. Proměnná prostředí v registru ale přetrvá, dokud ji uživatel neodebere programově nebo prostřednictvím nástroje operačního systému.However, the environment variable in the registry persists until a user removes it programmatically or by means of an operating system tool.

    V systémech UNIX se pokus o vytvoření proměnné vyhledáte s EnvironmentVariable.Machine žádným účinkem neprojeví a pokus o načtení proměnné vyhledáte pomocí EnvironmentVariable.Machine funkce Returns null (in C#) nebo Nothing (v Visual Basic).On Unix-based systems, an attempt to create an enviroment variable with EnvironmentVariable.Machine has no effect, and an attempt to retrieve an enviroment variable using EnvironmentVariable.Machine returns null (in C#) or Nothing (in Visual Basic).

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