Where is my core file?

Recently i was testing jemalloc for detecting memory corruptions of the program.This was tested by writing programs that intentionally crash and looking for jemalloc to abort and raise errors.

On my ubuntu machine, i found that program was not generating core. I was confused. So the first thing to check is to ulimit.

pradheep@PradheepVM:~/jemalloc$ ulimit
unlimited 

The default output says unlimited. So looked at the man page of bash(1) this defaults to -f which is “The maximum size of files written by the shell and its children”.

So looking at ulimit -a

 pradheep@PradheepVM:/$ ulimit -a  
 core file size     (blocks, -c) 0 
 data seg size      (kbytes, -d) unlimited  
 scheduling priority       (-e) 0  

Now we need to set the core value to unlimited.This can be done using ulimit -c unlimited

The output should be

pradheep@PradheepVM:/$ ulimit -a  
 core file size     (blocks, -c) unlimited  
 data seg size      (kbytes, -d) unlimited  
 scheduling priority       (-e) 0  
 file size        (blocks, -f) unlimited  
 pending signals         (-i) 7402  
 max locked memory    (kbytes, -l) 64  
 max memory size     (kbytes, -m) unlimited  
 open files           (-n) 1024  
 pipe size      (512 bytes, -p) 8  

This is set only on the shell you have run, to set the value permentenly on all the new shells that are spawned you should edit $HOME/.bashrc to add ulimit -c unlimited

In all your new shell invocation you will be provided with unlimited core size dump.

More info on setting core dump can be found here.

Additional info on core file dumps can be found in the following links

1. [http://stackoverflow.com/questions/7732983/core-dump-file-is-not-generated] (http://stackoverflow.com/questions/7732983/core-dump-file-is-not-generated).
2. [http://askubuntu.com/questions/295765/upstart-and-core-files] (http://askubuntu.com/questions/295765/upstart-and-core-files).