先说下周二晚上一个有意思的事情——大娃的U盘和移动硬盘中病毒了，文件查看不到，只留下一个无法运行的.exe文件，使用360 U助手能扫描到文件。本来按照官方教程准备备份数据，欲摆开架势开干，然后看流程还挺复杂的，就拿U盘小试牛刀，结果失败了。问题不大，失败不是常有的嘛~于是放弃了，开始谷歌，开始漫漫尝试。最终在试了两三次之后，使用管理员权限，运行解除隐藏文件的命令，将文件重新恢复显示。
然后有了这样一个问题：为什么U盘不带防火墙？我平常主要使用Linux系统开发，是在Windows上装的虚拟机，由于工作需要，装了10个虚拟机。。。当然了，有几个是“过程虚拟机”，学会之后要删掉的。平时一些软件需要，我的防火墙都是关闭的，感觉病毒威胁还好。。再之前ubuntu的ssh端口使用了默认端口，被病毒入侵开始挖矿，大概就这些了。说回U盘防火墙，以自己的理解，它是一个被挂载的设备，本身没有运行能力，需要其他宿主来加载，有点类似一个库。
以下所述均主要在Linux平台。
以目前所接触的编程来看，尤其稍大一点儿的UI程序，偶尔操作就会发生闪退，这块不一定是段错误。闪退不一定是段错误，但段错误一定会崩。
先追溯一些历史：
Stackoverflow：What is a segmentation fault?
What is a segmentation fault? Is it different in C and C ? How are segmentation faults and dangling pointers related?
Segmentation fault is a specific kind of error caused by accessing memory that “does not belong to you.” It’s a helper mechanism that keeps you from corrupting the memory and introducing hard-to-debug memory bugs. Whenever you get a segfault you know you are doing something wrong with memory – accessing a variable that has already been freed, writing to a read-only portion of the memory, etc. Segmentation fault is essentially the same in most languages that let you mess with memory management, there is no principal difference between segfaults in C and C .
There are many ways to get a segfault, at least in the lower-level languages such as C( ). Acommon way to get a segfault is to dereference a null pointer:
代码语言：javascript复制int *p = NULL;
*p = 1;Another segfault happens when you try to write to a portion of memory that was marked as read-only:
代码语言：javascript复制char *str = "Foo"; // Compiler marks the constant string as read-only
*str = 'b'; // Which means this is illegal and results in a segfaultDangling pointer points to a thing that does not exist anymore, like here:
代码语言：javascript复制char *p = NULL;
{
char c;
p = &c;
}// Now p is danglingThe pointer p dangles because it points to the character variable c that ceased to exist after the block ended. And when you try to dereference dangling pointer (like *p='A'), you would probably get a segfault.
上述资料仅用于交流学习，勿商用。
文章仅讨论软件引发的段错误。
简单概述，段错误是访问本来你不应该访问的区域，像只读数据段进行写操作，对空指针进行赋值操作等。
对于编程序的人来说，必现的错误不难解决，难解决的是偶发的问题。一些设备销售出去，当发生闪退时，可以记录闪退位置，如果频繁发生一些问题，软件可以用debug模式编译。更具较优的选择可能是自动化测试，防患于未然。本次先抛砖引玉，下次使用具体例子展示如何记录段错误信息。
喜欢分享，我是大贺！
