# :-: core文件设置 | 适用范围 | 适用版本 | 人员 | 发布时间 | 文档版本 |备注 | | --- | --- | --- | --- | --- |--- | | 服务器操作系统 | V7、V10、V10-SP1 | 王承林 |2022.3.4| V1.0|发布| | 服务器操作系统 | V7、V10、V10-SP1 | 张志勇 |2022.3.4| V1.1|模板调整| ### 经测试，该方案有效可行 ***** ## 在Linux中，一般当进程非正常退出时，会生成一个core文件，这个文件是进程猝死时内存的转储文件，也称为core dump ### 1. 查看是否开启core dump `[root@ceph1 ~]# ulimit -c unlimited` #只要这里显示的值不会0即开启, 为unlimited代表不限制最后的core文件大小. ### 2. 手动开启core dump #### 2.1 手动开启 ``` [root@ceph1 ~]# echo "ulimit -c unlimited" >> /etc/profile [root@ceph1 ~]# source /etc/profile [root@ceph1 ~]# ulimit -c unlimited ``` #### 2.2 生成文件尾缀是否带pid,为0则不带,为1则带 ``` [root@ceph1 ~]# sysctl -a | grep kernel.core_uses_pid kernel.core_uses_pid = 1 ``` #### 2.3 指定生成文件的路径 ``` [root@ceph1 ~]# echo 'kernel.core_pattern=/var/crash/core.%e.%p.%t' >> /etc/sysctl.conf && sysctl -p kernel.sysrq = 0 net.ipv4.ip_forward = 0 net.ipv4.conf.all.send_redirects = 0 net.ipv4.conf.default.send_redirects = 0 net.ipv4.conf.all.accept_source_route = 0 net.ipv4.conf.default.accept_source_route = 0 net.ipv4.conf.all.accept_redirects = 0 net.ipv4.conf.default.accept_redirects = 0 net.ipv4.conf.all.secure_redirects = 0 net.ipv4.conf.default.secure_redirects = 0 net.ipv4.icmp_echo_ignore_broadcasts = 1 net.ipv4.icmp_ignore_bogus_error_responses = 1 net.ipv4.conf.all.rp_filter = 1 net.ipv4.conf.default.rp_filter = 1 net.ipv4.tcp_syncookies = 1 kernel.dmesg_restrict = 1 net.ipv6.conf.all.accept_redirects = 0 net.ipv6.conf.default.accept_redirects = 0 net.ipv4.icmp_echo_ignore_all = 0 kernel.core_pattern = /var/crash/core.%e.%p.%t ``` #### 2.4 关键参数含义介绍 ``` kernel.core_pattern #指定路径,其中的特殊变量为: %p #– insert pid into filename --- 显示进程号 %u #– insert current uid into filename --- 用户ID %g #– insert current gid into filename --- 组ID %s #– insert signal that caused the coredump into the filename ---添加导致产生core的信号 %t #– insert UNIX time that the coredump occurred into filename --- 时 间 %h #– insert hostname where the coredump happened into filename --- 主机名 %e #– insert coredumping executable name into filename --- 名字 ``` ### 3. 手动生成core dump文件 #### 3.1 写入一个可以生成段错误的测试程序 `[root@ceph1 ~]# cat << EOF >> /root/a.c` ``` #include <stdio.h> int func(int *p) { *p = 0; } int main() { func(NULL); return 0; } EOF ``` #### 3.2 编译,执行 ``` [root@ceph1 ~]# gcc -o main a.c [root@ceph1 ~]# ./main Segmentation fault (core dumped) ``` #### 3.3 查看生成了core dump文件 ``` [root@ceph1 ~]# ls /var/crash/ core.main.10662.1643110445 ``` ### 4. 查询core dump文件内容 `[root@ceph1 ~]# yum install gdb -y`   #### 3.2 执行命令查询定位分析程序 #定位分析发现是 ``` [root@ceph1 ~]# gdb main /var/crash/core.main.10662.1643110445 GNU gdb (GDB) EulerOS 8.3.1-11.oe1 Copyright (C) 2019 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-openEuler-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. Find the GDB manual and other documentation resources online at: <http://www.gnu.org/software/gdb/documentation/>. For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from main... (No debugging symbols found in main) [New LWP 10662] Core was generated by `./main' Program terminated with signal SIGSEGV, Segmentation fault. #0 0x0000000000401126 in func () # ***这里定位到func()这个函数出现错误 #Missing separate debuginfos, use: dnf debuginfo-install glibc-2.28-36.oe1.x86_64 ``` #### 3.3 补充,可以在编译程序时候加上-g 然后在gdb时候过程更加快速定位错误所在 ``` [root@ceph1 ~]# rm -rf main [root@ceph1 ~]# gcc -o main -g a.c [root@ceph1 ~]# ./main Segmentation fault (core dumped) [root@ceph1 ~]# ls /var/crash/core.main.10 core.main.10662.1643110445 core.main.10885.1643111001 [root@ceph1 ~]# ls /var/crash/core.main.10885.1643111001 /var/crash/core.main.10885.1643111001 [root@ceph1 ~]# gdb main /var/crash/core.main.10885.1643111001 GNU gdb (GDB) EulerOS 8.3.1-11.oe1 Copyright (C) 2019 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-openEuler-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. Find the GDB manual and other documentation resources online at: <http://www.gnu.org/software/gdb/documentation/>. For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from main... [New LWP 10885] Core was generated by `./main'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x0000000000401126 in func (p=0x0) at a.c:9 9 *p = 0; Missing separate debuginfos, use: dnf debuginfo-install glibc-2.28-36.oe1.x86_64 ```