无法理解“杀戮" Linux程序 [英] Unable to understand the "Kill" program of linux

问题描述

这是一个非常小的与"kill"相关的程序.该程序正在执行，但无法弄清楚代码.任何人都可以让我理解下面的代码.

Here is a very small "kill" related program .The program is executing but am unable to figure out the code.Can any one please make me understand the code below.

int main(int argc ,char **argv)
{
  if(argc < 2)
  {
    printf("usage : ./kill PID");
    return -1;
  }
  kill(atoi(argv[1]),SIGKILL);
  return 0;
}

推荐答案

基本上，它只是检查是否提供了参数. if(argc < 2)表示程序的参数少于两个.请注意，程序名称本身也是一个参数，这就是为什么它是argc < 2而不是argc < 1的原因.确定后，将调用内置kill函数.此方法的第一个参数是整数，这就是为什么第二个参数(PID，表示为字符串)使用atoi解析为整数的原因. kill的第二个参数是信号，在这种情况下为SIGKILL.也可以使用其他信号，例如SIGHUP，但是由于该程序杀死"了它，所以使用了SIGKILL.

Basically, it just checks to see if an argument has been provided. if(argc < 2) means are there less than two arguments to the program. Note that the program name itself is an argument too, which is why it's argc < 2 and not argc < 1. Once this has been determined the builtin kill function is called. The first argument to this method is an integer, which is why the second argument (the PID, represented as a string) is parsed to an integer with atoi. The second argument to kill is the signal, in this case SIGKILL. Other signals, such as SIGHUP could also have been used, but since this program "kills", it uses SIGKILL.

这篇关于无法理解“杀戮" Linux程序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！