The default core dump file size is 0 on Debian Linux:
$ ulimit -c
0
To enable generating core dump file, I need to run following command:
$ ulimit -c unlimited
But if you re-login, the core dump file size is changed back to 0 from unlimited. So “ulimit -c unlimited” need to be executed during your login. E.g., if you use zsh, append it in .zshrc file.