# 获取MySQL core

> 本文是为DB开发同学设置mysql core的笔记，当时环境`kill -11 ${pidof mysqld}`没有正确生成core文件，所以对环境做了检查。

## 尝试

* 检查环境，发现好像是 `suid_dumpable`没有设置正确

```
-bash-4.1$ cat /proc/sys/fs/suid_dumpable
0
```

使用root身份修改

```
echo 2 > /proc/sys/fs/suid_dumpable
```

* 切换到root用户

```
mkdir /tmp/corefiles
chmod 777 /tmp/corefiles
echo “/tmp/corefiles/core” > /proc/sys/kernel/core_pattern
```

> 我检查环境原先 `/proc/sys/kernel/core_pattern` 就是 `/tmp/corefiles/core`
>
> 原先 `/proc/sys/kernel/core_uses_pid` 值就是 `1`

再验证一遍环境

```
-bash-4.1$ cat /proc/sys/fs/suid_dumpable
2
-bash-4.1$ cat /proc/sys/kernel/core_pattern
/tmp/corefiles/core
-bash-4.1$ cat /proc/sys/kernel/core_uses_pid
1
```

* 杀进程触发

```
kill -sigsegv `pidof mysqld`
```

发现`-sigsegv`没有反应，改为`-11`

```
kill -11 `pidof mysqld`
```

此时再看`/tmp/corefiles`目录下就生成了`core.14549` （这个pid就是被杀死pid对应的core文件）

## 参考

* [Getting MySQL Core file on Linux](https://www.percona.com/blog/2011/08/26/getting-mysql-core-file-on-linux/)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://huataihuang.gitbook.io/cloud-atlas-draft/os/linux/kernel/tracing/mysql_core.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.