检查是否打开core
没有打开的例子：
[root@senbo088]# ulimit -c
0
[root@senbo088]# ./test
Segmentation fault
打开之后的例子：
[root@senbo088]# ulimit -c unlimited
0
[root@senbo088]# ulimit -c
unlimited
[root@senbo088]# ./test
Segmentation fault (core dumped)
检查core 的路径
一种典型而又及其隐蔽的core不dump的错误是 修改了core dump的默认路径，但是目录不存在。
如下这种情况：
[root@senbo088]# ulimit -c
unlimited
[root@senbo088]# ./test
Segmentation fault
[root@senbo088]# sysctl -p
排查过程如下：
net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
error: "net.bridge.bridge-nf-call-ip6tables" is an unknown key
error: "net.bridge.bridge-nf-call-iptables" is an unknown key
error: "net.bridge.bridge-nf-call-arptables" is an unknown key
kernel.printk = 0
kernel.printk = 0
kernel.corepattern = /var/core/core%e_%p
kernel.core_uses_pid = 0
[root@senbo088]# ls /var/core
ls: cannot access /var/core: No such file or directory
创建 /var/core目录之后，就好了：
[root@senbo088]# mkdir -p /var/core/
[root@senbo088]# ./test
Segmentation fault (core dumped)
为了支持core 最好打开-ggdb编译选项
必需 -g / -ggdb 支持；