How to allow application cores in Big Sur

Question

Created Feb ’21

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How do I enable core dumps, persistently, in Big Sur.

I am more versed in *nix/linux than macOS. I've had a few apps core dump, and see in the 'Console' that they are not permitted to create core files.

I've tried 'ulimit -c unlimited' but this hasn't been perspective - perhaps in part as I'm unsure how to get this persistent for all apps (even outside a login shell) on Big Sur.

Is there a simple guide to allowing core dumps ie into /cores as I was able to get that working in previous releases...

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Answer 1

DTS Engineer OP

Apple

Feb ’21

The /cores directory is only writable by root:

Code Block  % ls -ld /cores
drwxr-xr-x  3 root  wheel  96 26 Feb 10:34 /cores

So you only get a core dump when the process is running as root:

Code Block  % ulimit -c unlimited
% ./crash
zsh: abort      ./crash
% ls -lha /cores
total 0
drwxr-xr-x   2 root  wheel    64B 13 Dec  2019 .
drwxr-xr-x  20 root  wheel   640B  1 Jan  2020 ..
% # No core!
%
% sudo ./crash
% ls -lha /cores
total 4900984
drwxr-xr-x   3 root  wheel    96B 26 Feb 10:34 .
drwxr-xr-x  20 root  wheel   640B  1 Jan  2020 ..
-r--------   1 root  wheel   2.3G 26 Feb 10:35 core.21226
% # Now we get a core.

You can change the owner and permissions of /cores if you want:

Code Block  % sudo chown :staff /cores
% sudo chmod g+w /cores
% ls -ld /cores
drwxrwxr-x  2 root  staff  64 Jan  1  2020 /cores

Personally I only do this in a VM. I prefer not to make system-wide configuration changes on my main Mac.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

0

Answer 2

PrasannaBK OP

Oct ’21

I have tried 'ulimit -c unlimited' and couple of other things mentioned in various forums. I have checked that /cores folder has write permissions. Still I couldn't manage to generate the core dumps for the crash on macOS bigsur 11.5.2. @eskimo Can you please list the steps required to enable the core dump on macOS bigsur 11.5.2 ?

more info from my machine

kern.corefile: /cores/core.%P
kern.coredump: 1
kern.sugid_coredump: 0
machdep.cpu.thermal.core_power_limits: 1
machdep.cpu.core_count: 8
machdep.cpu.cores_per_package: 8

launchctl limit                                                                                                                                                                                                                                                        
	cpu         unlimited      unlimited
	filesize    unlimited      unlimited
	data        unlimited      unlimited
	stack       8388608        67104768
	core        0              unlimited
	rss         unlimited      unlimited
	memlock     unlimited      unlimited
	maxproc     5568           8352

drwxrwxrwx   2 root  staff    64B Oct 20 19:21 cores

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