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I have a C++ program that does what it is supposed to do, but there must be some problem with pointer, since it crashes at the end and creates a core dump. My problem is that I cannot find the core file, so I cannot debug it.

I have tried 

ulimit -c unlimited
ulimit -a

and now the dimension of the file is set to unlimited, but still I cannot find the core. I have tried in every folder written here but still it seems that no core file is created.

Where can I find it?

mattiav27
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3 Answers3

36

In Ubuntu the core dumps are handled by Apport and can be located in /var/crash/. But it is disabled by default in stable releases.

To enable Apport, run: sudo systemctl enable apport.service or sudo service apport start.

To disable, run: sudo systemctl disable apport.service or sudo service apport stop in order to back to regular core dumping method. See: How do I enable or disable Apport?.

To disable permanently, edit /etc/apport/crashdb.conf file and comment the following line:

'problem_types': ['Bug', 'Package'],

by adding a hash symbol (#) in the beginning of the line.

To disable crash reporting (set it back to normal), remove the hash symbol to revert the change.

You can also check core_pattern, how core dumps are handled by the kernel:

$ cat /proc/sys/kernel/core_pattern
|/usr/share/apport/apport %p %s %c

So even if core files are disabled by ulimit, apport will still capture the crash.

See also:

alexh
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kenorb
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19

All the above did not worked for me... I looked at /var/log/apport.log:

cat /var/log/apport.log

and I saw the file name:

ERROR: apport (pid 3426) Mon Nov  8 14:34:07 2021: writing core dump to core._home_guest_a_out.1000.4 ...

and then I search throughout all the system

sudo find . -name "core._home_guest_a_out.1000.4..."

I found the core dump in /var/lib/apport/coredump/

Community
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yehudahs
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10

For those googlin': ( in my case -- Ubuntu 16.04 and 18.04 and a custom app ) /var/crash was still empty, so a quick way to handle core creation ( provided that you are e.g. using a relevant ulimit builtin setting ) was

sudo sysctl -w kernel.core_pattern=core.%u.%p.%t # to enable core generation

and 

systemctl restart apport # to restore default apport settings
# which, by the way, were "|/usr/share/apport/apport %p %s %c %d %P" (without quotes)

Sources:
ジョージ
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