问题
Friends,
I'm trying to set the environment variable "asdf" in my Scala shell, as described here
These are my commands:
scala> import scala.sys.process.Process
import scala.sys.process.Process
scala> Process(Seq("bash", "-c", "echo $asdf"), None, "asdf" -> "Hello, world!").!
Hello, world!
res18: Int = 0
But when i try to read the environment variable back:
scala> sys.env.get("asdf")
res19: Option[String] = None
The output says "None". How do i properly set my environment variable in the current session?
PS - Please do not downvote this; i'm trying really hard but unable to get past my issue
回答1:
It is not permitted for a Scala/Java process to modify its own environment. You can use the scala.util.Properties object to inspect environmental variables and properties. (Docs are here.) The properties can be added/removed/changed but the environmentals cannot.
回答2:
It has nothing to do with Scala, you are just misunderstanding the situation. The map at the end of the line
scala> Process(Seq("bash", "-c", "echo $asdf"), None, "asdf" -> "Hello, world!").!
doesn't change the environment of of this process, the one you are typing into; it changes the environment of the child process that the Process() function creates.
来源：https://stackoverflow.com/questions/42639105/scala-unable-to-set-environment-variable