如何在 C# 中获取和设置环境变量？
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How do I get and set Environment variables in C#?
提问by Mister Dev
How can I get Environnment variables and if something is missing, set the value?
如何获取环境变量，如果缺少某些内容，请设置值？
采纳答案by Patrick Desjardins
Use the System.Environmentclass.
The methods
方法
var value = System.Environment.GetEnvironmentVariable(variable [, Target])
and
和
System.Environment.SetEnvironmentVariable(variable, value [, Target])
will do the job for you.
会为你做这项工作。
The optional parameter Targetis an enum of type EnvironmentVariableTargetand it can be one of: Machine, Process, or User. If you omit it, the default target is the current process.
可选参数Target是类型的枚举EnvironmentVariableTarget，它可以是以下之一：Machine，Process，或User。如果省略它，则默认目标是当前进程。
回答by SpeedyNinja
This will work for an environment variable that is machine setting. For Users, just change to User instead.
这将适用于机器设置的环境变量。对于用户，只需改为用户即可。
String EnvironmentPath = System.Environment
.GetEnvironmentVariable("Variable_Name", EnvironmentVariableTarget.Machine);
回答by Nathan Bedford
I ran into this while working on a .NET console app to read the PATH environment variable, and found that using System.Environment.GetEnvironmentVariable will expand the environment variables automatically.
我在使用 .NET 控制台应用程序读取 PATH 环境变量时遇到了这个问题，发现使用 System.Environment.GetEnvironmentVariable 会自动扩展环境变量。
I didn't want that to happen...that means folders in the path such as '%SystemRoot%\system32' were being re-written as 'C:\Windows\system32'. To get the un-expanded path, I had to use this:
我不希望这种情况发生……这意味着路径中的文件夹（例如“%SystemRoot%\system32”）被重写为“C:\Windows\system32”。为了获得未扩展的路径，我不得不使用这个：
string keyName = @"SYSTEM\CurrentControlSet\Control\Session Manager\Environment\";
string existingPathFolderVariable = (string)Registry.LocalMachine.OpenSubKey(keyName).GetValue("PATH", "", RegistryValueOptions.DoNotExpandEnvironmentNames);
Worked like a charm for me.
对我来说就像一种魅力。
回答by Karthik Chintala
Environment.SetEnvironmentVariable("Variable name", value, EnvironmentVariableTarget.User);
回答by Tom Stickel
Get and Set
获取和设置
Get
得到
string getEnv = Environment.GetEnvironmentVariable("envVar");
Set
放
string setEnv = Environment.SetEnvironmentVariable("envvar", varEnv);
回答by Ajit
I could be able to update the environment variable by using the following
我可以使用以下方法更新环境变量
string EnvPath = System.Environment.GetEnvironmentVariable("PATH", EnvironmentVariableTarget.Machine) ?? string.Empty;
if (!string.IsNullOrEmpty(EnvPath) && !EnvPath .EndsWith(";"))
EnvPath = EnvPath + ';';
EnvPath = EnvPath + @"C:\Test";
Environment.SetEnvironmentVariable("PATH", EnvPath , EnvironmentVariableTarget.Machine);
