Java 中的 ProcessBuilder 环境变量
2022-09-03 00:46:53
我正在尝试为 ProcessBuilder 对象添加环境变量,但是当我在 ProcessBuilder 中调用该新变量时,我收到一个错误。这就是我构建流程的方式
public class OTU
{
public static void main(String[] args) throws Exception
{
ProcessBuilder pb = new ProcessBuilder();
Map<String, String> env = pb.environment();
//set environment variable u
env.put("u", "util/");
pb.command("echo $u");
Process p = pb.start();
String output = loadStream(p.getInputStream());
String error = loadStream(p.getErrorStream());
int rc = p.waitFor();
System.out.println("Process ended with rc=" + rc);
System.out.println("\nStandard Output:\n");
System.out.println(output);
System.out.println("\nStandard Error:\n");
System.out.println(error);
}
private static String loadStream(InputStream s) throws Exception
{
BufferedReader br = new BufferedReader(new InputStreamReader(s));
StringBuilder sb = new StringBuilder();
String line;
while((line=br.readLine()) != null)
sb.append(line).append("\n");
return sb.toString();
}
}
我收到错误
Exception in thread "main" java.io.IOException: Cannot run program "$u": java.io.IOException: error=2, No such file or directory
at java.lang.ProcessBuilder.start(ProcessBuilder.java:475)
at ca.utoronto.siseq_1_2.OTU.main(OTU.java:22)
Caused by: java.io.IOException: java.io.IOException: error=2, No such file or directory
at java.lang.UNIXProcess.<init>(UNIXProcess.java:164)
at java.lang.ProcessImpl.start(ProcessImpl.java:81)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:468)
... 1 more
我不明白为什么如果我只为此进程设置变量,我会得到错误。请帮助我如何设置env变量,以便我可以在ProcessBuilder中使用它。