Java的执行exec（）不返回预期的管道'连接的命令结果 [英] Java exec() does not return expected result of pipes' connected commands

问题描述

我打电话是由管道连接的命令行程序。所有这一切在Linux是肯定的。

I'm calling command line programs connected by pipes. All this works on Linux for sure.

我的方法：

protected String execCommand(String command) throws IOException {
    String line = null;
    if (command.length() > 0) {
        Process child = Runtime.getRuntime().exec(command);
        InputStream lsOut = child.getInputStream();
        InputStreamReader r = new InputStreamReader(lsOut);
        BufferedReader in = new BufferedReader(r);

        String readline = null;
        while ((readline = in.readLine()) != null) {
            line = line + readline;
        }
    }

    return line;
}

如果我打电话给一些猫文件| grep的ASD 后，我得到预期的结果。但是，并非所有的命令正常工作。比如这个：

If I'm calling some cat file | grep asd, I'm getting the expected result. But not all commands works correctly. For example with this:

cat /proc/cpuinfo | wc -l

或本

cat /proc/cpuinfo | grep "model name" | head -n 1 | awk -F":" '{print substr($2, 2, length($2))}

该方法将返回null。我猜这个问题取决于输出格式化命令一样的头 尾 厕所，等我如何解决此问题，并得到输出的最终结果？

the method will return null. I'm guessing this problem depends on output formatting commands like head, tail, wc, etc. How I can work around this problem and get the final result of the output?

推荐答案

还是没有找到妥善的解决办法与执行的Runtime.exec管道命令，但发现了一个解决方法。我只是写了这些脚本分离的bash文件。随后的Runtime.exec调用这些的bash脚本，并得到预期的结果。

Still didn't found proper solution to execute piped commands with Runtime.exec, but found a workaround. I've simply wrote these scripts to separate bash files. Then Runtime.exec calls these bash scripts and gets expected result.

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