如何从Scala设置环境变量？

发布时间：2020-12-16 09:23:50 所属栏目：安全来源：网络整理

导读：我需要从Scala设置环境变量(PATH). 我试过这个： val cmd = Seq("export","PATH='bla'")cmd.lines 但是我得到了错误： java.io.IOException: Cannot run program "export": error=2,No such file or directoryat java.lang.ProcessBuilder.start(ProcessBuil

我需要从Scala设置环境变量(PATH).

我试过这个：

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

但是我得到了错误：

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

还有其他方法吗？

解决方法

来自sys.process.Process的doc的示例：

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

编辑更有用的措辞：

也就是说,在生成子进程时指定env.

当前进程的环境是只读的;请参阅System.getenv,或比较抽象sys.props和sys.env.

shell增加了它在导出变量的子shell上赋予的环境这一事实是一种shell约定.参见bash参考中的3.7.4,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.

这是我的答案第一次超过the Daniel Sobral answer重复.

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!