Core dump file is not generated

Question

Every time, my application crash a core dump file is not generated. I remember that few days ago, on another server it was generated. I\'m running the app u

Answer 1

Check:

$ sysctl kernel.core_pattern

to see how your dumps are created (%e will be the process name, and %t will be the system time).

If you've Ubuntu, your dumps are created by apport in /var/crash, but in different format (edit the file to see it).

You can test it by:

sleep 10 &
killall -SIGSEGV sleep

If core dumping is successful, you will see “(core dumped)” after the segmentation fault indication.

Read more:

How to generate core dump file in Ubuntu

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Ubuntu

Please read more at:

https://wiki.ubuntu.com/Apport

Answer 2

Note: If you have written any crash handler yourself, then the core might not get generated. So search for code with something on the line:

signal(SIGSEGV, <handler> );

so the SIGSEGV will be handled by handler and you will not get the core dump.

Answer 3

Make sure your current directory (at the time of crash -- server may change directories) is writable. If the server calls setuid, the directory has to be writable by that user.

Also check /proc/sys/kernel/core_pattern. That may redirect core dumps to another directory, and that directory must be writable. More info here.

Answer 4

If you call daemon() and then daemonize a process, by default the current working directory will change to /. So if your program is a daemon then you should be looking for a core in / directory and not in the directory of the binary.

Answer 5

Although this isn't going to be a problem for the person who asked the question, because they ran the program that was to produce the core file in a script with the ulimit command, I'd like to document that the ulimit command is specific to the shell in which you run it (like environment variables). I spent way too much time running ulimit and sysctl and stuff in one shell, and the command that I wanted to dump core in the other shell, and wondering why the core file was not produced.

I will be adding it to my bashrc. The sysctl works for all processes once it is issued, but the ulimit only works for the shell in which it is issued (maybe also the descendents too) - but not for other shells that happen to be running.

Answer 6

If one is on a Linux distro (e.g. CentOS, Debian) then perhaps the most accessible way to find out about core files and related conditions is in the man page. Just run the following command from a terminal:

man 5 core