如何從Scala設置環境變量？

Question

我需要從Scala設置環境變量（PATH）。

我嘗試這樣做：

val cmd = Seq("export", "PATH='bla'") 
cmd.lines 

但我得到的錯誤：

java.io.IOException: Cannot run program "export": error=2, No such file or directory 
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1041) 
at scala.sys.process.ProcessBuilderImpl$Simple.run(ProcessBuilderImpl.scala:68) 
at scala.sys.process.ProcessBuilderImpl$AbstractBuilder.lines(ProcessBuilderImpl.scala:140) 
at scala.sys.process.ProcessBuilderImpl$AbstractBuilder.lines(ProcessBuilderImpl.scala:106) 
at .<init>(<console>:12) 
at .<clinit>(<console>) 
at .<init>(<console>:11) 
at .<clinit>(<console>) 
at $print(<console>) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:606) 
at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:704) 
at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:914) 
at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:546) 
at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:577) 
at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:543) 
at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:694) 
at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:745) 
at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:651) 
at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:542) 
at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:550) 
at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822) 
at scala.tools.nsc.interpreter.ILoop.main(ILoop.scala:851) 
at xsbt.ConsoleInterface.run(ConsoleInterface.scala:57) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:606) 
at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:73) 
at sbt.compiler.AnalyzingCompiler.console(AnalyzingCompiler.scala:64) 
at sbt.Console.console0$1(Console.scala:23) 
at sbt.Console$$anonfun$apply$2$$anonfun$apply$1.apply$mcV$sp(Console.scala:24) 
at sbt.TrapExit$.executeMain$1(TrapExit.scala:33) 
at sbt.TrapExit$$anon$1.run(TrapExit.scala:42) 
Caused by: java.io.IOException: error=2, No such file or directory 
    at java.lang.UNIXProcess.forkAndExec(Native Method) 
    at java.lang.UNIXProcess.<init>(UNIXProcess.java:135) 
    at java.lang.ProcessImpl.start(ProcessImpl.java:130) 
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1022) 
    ... 35 more 

有一些其他的方法呢？從文檔

Answer 1

舉例sys.process.Process：

apply("java", new java.ioFile("/opt/app"), "CLASSPATH" -> "library.jar") 

編輯爲更有幫助的措辭：

也就是說，當您生成一個子進程指定ENV。

當前進程的環境是隻讀的;見System.getenv，或比較抽象sys.props和sys.env。

事實上，一個shell增加了它在賦予導出變量的subshel​​l上賦予的環境是一個shell約定。見3.7.4在bash的引用，例如：

On invocation, the shell scans its own environment and creates a parameter for each name found, automatically marking it for export to child processes. Executed commands inherit the environment. The export and ‘declare -x’ commands allow parameters and functions to be added to and deleted from the environment. If the value of a parameter in the environment is modified, the new value becomes part of the environment, replacing the old. The environment inherited by any executed command consists of the shell's initial environment, whose values may be modified in the shell, less any pairs removed by the unset and ‘export -n’ commands, plus any additions via the export and ‘declare -x’ commands.

這是第一次我的回答是長於the Daniel Sobral answer它複製。

Answer 2

'export'不是可執行文件，它是一個shell內置命令。如果你試圖在父shell中設置路徑，那麼你不能。您可以將其設置爲您執行的新shell。這實際上更像是一個unix FAQ。