一、编译程序（-g -rdynamic）
编译源代码时指定
-g -rdynamic参数，编译带有调试信息的可执行程序
二、打开core dump限制
1、通过指令打开
使用
ulimit -a指令来查看系统相关的限制参数。
[11:05@zhouchao ~/c_c++]$ulimit -a
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 30773
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 65535
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 4096
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
==注意==：通过
ulimit -c unlimited、ulimit -c 1024、ulimit -c 0等指令来配置core dump功能，其中unlimited表示不限制，1024表示最多1024个块，0表示关闭该功能。
2、修改配置文件
修改配置文件
/etc/security/limits.conf,找到#* soft core 0修改为#* soft core unlimited即可。
注意：该配置文件是一个只读文件，需要root权限chmod后才能修改内容。
50 #<domain> <type> <item> <value>
51 #
52
53 #* soft core 0
54 #* hard rss 10000
55 #@student hard nproc 20
56 #@faculty soft nproc 20
57 #@faculty hard nproc 50
58 #ftp hard nproc 0
三、core文件名称和路径
默认生成路径：可执行文件运行命令的同一路径。
默认生成名称：core，新的文件会覆盖就的core文件。
1、设置pid作为文件扩展名
root权限下修改
/proc/sys/kernel/core_uses_pid文件内容为1或0.
sysctl -w kernel.core_uses_pid=1
echo "0" > /proc/sys/kernel/core_uses_pid1：添加pid作为文件扩展名，生成core文件为
core.pid.
0：不添加pid作为文件扩展名，生成core文件为core.
[11:19@root ~]$cat /proc/sys/kernel/core_uses_pid
0
[11:20@root ~]$sysctl -w kernel.core_uses_pid=1
kernel.core_uses_pid = 1
[11:20@root ~]$cat /proc/sys/kernel/core_uses_pid
1
[11:20@root ~]$echo "0" > /proc/sys/kernel/core_uses_pid
[11:20@root ~]$cat /proc/sys/kernel/core_uses_pid
0
[11:20@root ~]$
2、控制core文件的保存为之和文件名格式
root权限下修改
/proc/sys/kernel/core_pattern文件内容.
echo "/corefile/core-%e-%p-%t" > /proc/sys/kernel/core_pattern
sysctl -w kernel.core_pattern=/corefile/core.%e.%p.%s.%E%p：进程ID(4206)
%u：用户ID(1002)
%g：用户组ID(1000)
%s：添加导致产生core的信号(11)
%t：添加core文件生成时的Unix时间(1640230181)
%h：添加主机名(localhost.localdomain)
%e：添加导致产生core的命令名（seg.bin）
[11:28@root ~]$cat /proc/sys/kernel/core_pattern
core.%e.%p.%u.%s.%g.%h.%t.%E
[11:28@root ~]$sysctl -w kernel.core_pattern=core.%e.%p.%u.%s.%g.%h.%t
kernel.core_pattern = core.%e.%p.%u.%s.%g.%h.%t
[11:33@root ~]$echo "core.%e.%p.%u.%s.%g.%h.%t" > /proc/sys/kernel/core_pattern
[11:34@root ~]$cat /proc/sys/kernel/core_pattern
core.%e.%p.%u.%s.%g.%h.%t
[11:34@root ~]$ls
core.seg.bin.13042.1002.11.1000.localhost.localdomain.1640230507
3、测试是否生效
执行
kill -s SIGSEGV $$指令，查看当前目录下是否生成了core文件。
[11:34@root ~]$kill -s SIGSEGV $$
Segmentation fault (core dumped)
[11:37@zhouchao ~/c_c++]$ls
core.bash.2697.1002.11.1000.localhost.localdomain.1640230610
[11:39@zhouchao ~/c_c++]$gdb -q bash core.bash.2697.1002.11.1000.localhost.localdomain.1640230610
Reading symbols from bash...
Reading symbols from .gnu_debugdata for /usr/bin/bash...
(No debugging symbols found in .gnu_debugdata for /usr/bin/bash)
[New LWP 2697]
Core was generated by `-bash'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007f5d0d8df6a7 in kill () from /usr/lib64/libc.so.6
(gdb) bt
#0 0x00007f5d0d8df6a7 in kill () from /usr/lib64/libc.so.6
#1 0x0000000000433bab in execute_command ()
#2 0x000000000041e285 in reader_loop ()
#3 0x000000000041c8ee in main ()
(gdb) _
四、通过core文件排查错误
执行
gdb [exec-file] [core-file]或gdb -c [core-file] [exec-file]指令来查看core文件内容，通过bt指令查看堆栈信息。
[11:45@zhouchao ~/c_c++]$gdb -q ./seg core.seg.27060.11.1640231023
Reading symbols from ./seg...
[New LWP 27060]
Core was generated by `./seg'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000000000400885 in test_ptr (ptr=0x0) at test.c:21
21 printf("ptr = %p, a = %u, b = %f.\n", ptr, ptr->a, (*ptr).b);
(gdb) bt
#0 0x0000000000400885 in test_ptr (ptr=0x0) at test.c:21
#1 0x0000000000400912 in main () at test.c:33
(gdb) q
[11:46@zhouchao ~/c_c++]$gdb -q -c core.seg.27060.11.1640231023 ./seg
Reading symbols from ./seg...
[New LWP 27060]
Core was generated by `./seg'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000000000400885 in test_ptr (ptr=0x0) at test.c:21
21 printf("ptr = %p, a = %u, b = %f.\n", ptr, ptr->a, (*ptr).b);
(gdb) bt
#0 0x0000000000400885 in test_ptr (ptr=0x0) at test.c:21
#1 0x0000000000400912 in main () at test.c:33
(gdb) q
[11:46@zhouchao ~/c_c++]$
