java - g++: 找不到文件

Question

我最近一直在开发一个程序，它可以从 Java 程序编译和运行 C++ 程序，基本上一切正常(或者至少据我所知)，但后来我注意到一些东西被打印到错误流中:

cdog5000@srv3:~$ java -Xmx50m -jar main2.jar
Running Command: sudo g++ --static -o "/home/cdog5000/cody.out" "/home/cdog5000/cody.cpp"
Err: g++: "/home/cdog5000/cody.cpp": No such file or directory
Err: g++: no input files


cdog5000@srv3:~$ ls -l
total 4548
-rwxr-xr-x 1 cdog5000 cdog5000 1297588 Feb  3 23:11 a.out
-rwxr-xr-x 1 cdog5000 cdog5000    7978 Feb  2 04:39 cody
-rw-r--r-- 1 cdog5000 cdog5000     106 Feb  4 02:09 cody.cpp
-rwxr-xr-x 1 cdog5000 cdog5000 1297357 Feb  4 02:09 cody.out
-rw-r--r-- 1 root     root      410433 Feb  4 02:48 log.txt
-rwxr-xr-x 1 cdog5000 cdog5000  801088 Feb  1 05:24 main.jar
-rw-r--r-- 1 cdog5000 cdog5000  804802 Feb  4 02:49 main2.jar
drwxr-xr-x 3 cdog5000 cdog5000    4096 Feb  3 23:11 sandbox
cdog5000@srv3:~$ sudo g++ --static -o "/home/cdog5000/cody.out" "/home/cdog5000/cody.cpp"

如您所见，如果我通过 SSH 而不是 Java 代码，它会起作用吗？

Java代码:

 public static Exec exec(String cmd){
        Exec exec = new Exec(cmd);
        try {
            long current = System.currentTimeMillis();
            Process proc = Runtime.getRuntime().exec(cmd);
            exec.setReturnValue(proc.waitFor());
            exec.setRunTime(System.currentTimeMillis() - current);
            BufferedInputStream bos = new BufferedInputStream(proc.getInputStream());
            byte b[] = new byte[1024];
            String content = "";
            while(bos.read(b) != -1) {
                content += new String(b);
            }
            exec.setStdIn(content.split("\n"));
            content = "";
            bos = new BufferedInputStream(proc.getErrorStream());

            while(bos.read(b) != -1) {
                content += new String(b);
            }
            exec.setStdErr(content.split("\n"));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return exec;
    }

感谢您的帮助，不胜感激!

Answer 1

Err: g++: "/home/cdog5000/cody.cpp": No such file or directory

告诉你问题所在。

你的一级引号太多，所以你正在寻找 "/home/cdog5000/cody.cpp" 而不是 /home/cdog5000/cody.cpp.

Runtime.exec documentation说:

More precisely, the command string is broken into tokens using a StringTokenizer created by the call new StringTokenizer(command) with no further modification of the character categories. The tokens produced by the tokenizer are then placed in the new string array cmdarray, in the same order.

这意味着它只在空格处拆分，它不像 shell 那样处理双引号。

许多语言都有两个函数，一个叫做 exec，它逐字运行命令，另一个叫做 system，它把字符串传递给 shell，在那里它会拆分单词和扩展通配符.

我在 Java 中看不到 system 调用，所以我认为您必须使用 exec(String[] cmdarray) 而不是 exec(字符串命令).