运行node的process.exit时候发现了以前忽视的一个问题：

$ node> process.exit(-1)$ echo $?255

我希望exit的值是-1,结果成了255。

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给出的解释：

Program return values mean different things on different operating systems. On Unix-y systems, only values 0-255 are valid (1 unsigned byte). Note this means negative values are not allowed, and may be the cause of your IDE problems. FreeBSD introduced a load of specific meanings in sysexits.h, and while this certainly exists on Linux distributions I've used, the only real universally accepted one is 0 for success and non-0 for failure. As Pete Becker points out, EXIT_SUCCESS and EXIT_FAILURE are standard defined macros (0 and 1 respectively on Unix-y platforms, but implementation defined).

On windows, you get a 32 bit signed integer (negatives are allowed, don't know if they mean anything). Again, 0 is success, and other values mean various things. Like echo $?, you can use echo %errorlevel% to see the last program's exit code in the console.

Also note that my N3337 (draft very close to C++11 standard) says at section 3.6.1 paragraph 5:

If control reaches the end of main without encountering a return statement, the effect is that of executing return 0;

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C语言示例：

示例1

#include 
    
     int main() {    return 0;}
    

退出码为0。

示例2

#include 
    
     int main() {    return -1;}
    

退出码为255.

示例3

#include 
    
     #include 
     
      int main() {    exit(-1);}
     
    

退出码为255.