shell命令执行从Java执行时失败 [英] shell Command execution Failing when executed from Java

问题描述

当我在命令行上执行以下命令时，它显示了sybase DB中的所有存储过程和表。

When I execute the below command on command line, it shows all the stored procedures and tables in the sybase DB.

printf 'sp_help\ngo\n' | isql -Uxx -Pxxxx -Dxxxxx

但是当我在java做同样的事情。这不返回任何结果。任何人都可以告诉我下面的代码有什么问题：

But when I do the same thing in java. This does not return any result. Can anyone tell me what is the problem with my code below:

public class test
{
  public static void main(String[] args)
  {
   String cmd = "printf "+"\'sp_help\ngo\n\'"+"| isql -Uxx -Pxxxx -Dxxxxx" ;
   try{ 
          Process p;
          p = Runtime.getRuntime().exec(cmd);
          p.waitFor();
          String line; 
          BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));

           while ((line = reader.readLine())!=null){
           System.out.println("Row is :" + line);
   } catch(Exception e)
       {
           System.out.println("Exception Caught : " + e);
       }

  }

}

EDIT
我按照Darkdust的建议执行它，但仍然无法正常工作。

EDIT I executed it as below suggested by Darkdust but still it doesnt work.

try{
          Process p;
          p = Runtime.getRuntime().exec("sh -c \'printf \"sp_help\ngo\n\" | isql -Uxx -Pxxxxx -Dxxxxxx\'");
          p.waitFor();
          String line;
          BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));

           while ((line = reader.readLine())!=null){
           System.out.println("Row is :" + line);
  }
 }
       catch(Exception e)
       {
           System.out.println("Exception Caught : " + e);
       }

但命令如下：

sh -c 'printf "sp_help\ngo\n" | isql -Usa -Psybase11 -Dcnadb'

可在命令行中使用。

我也试过：

p = Runtime.getRuntime().exec(new String[]{"sh","-c","\'printf \"sp_help\ngo\n\"","|isql -Uxx -Pxxxxx -Dxxxxx\'"});

但没有成功。

推荐答案

有几件事情想起来了：

• 不完整的PATH环境变量（因此 isql 找不到）。


• 如果它是一个命令，你提供，而不是搞乱PATH，你可能想确保你是在正确的工作目录并调用 ./ isql 。


• 由于你使用管道，你应该让shell执行这个 sh -cfoo | bar。否则 | isql ... 部分作为参数传递给 printf 。

• Incomplete PATH environment variable (thus isql can't be found).
• If it's a command you provide, instead of messing with PATH you might want to make sure your are you in the correct working directory and call ./isql instead.
• Since you're using a pipe, you should let a shell execute this as in sh -c "foo | bar". Otherwise the | isql ... part is passed as argument to printf as well.

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