core dump files, howto put in /tmp?

reakinator · 06-05-2008, 01:18 AM

Hi,

In trying to debug one of my favourite applications (ardour), it has been suggested to set 'ulimit -u unlimited' so that 'core' files are created after a crash. These files are big, normally around 50 megs, and they are littering my home directory.

I want to keep the setting on so that I can hand the core file to gdb when a backtrace is necessary, I just don't want them taking up valuable space.

So, is there a way to make the 'core' file written in /tmp always (thereby replacing a previous dump, and disappearing after a while)?

regards,
Rich

reakinator · 06-05-2008, 01:20 AM

ah, quick type. It is supposed to be "ulimit -c unlimited", but anyone who knows how to do what I am asking most definitely knows this too. anywho..

colucix · 06-05-2008, 02:12 AM

To change the location of the newly created core files, you have to change the content of /proc/sys/kernel/core_pattern:

Code:

sudo echo /tmp/core > /proc/sys/kernel/core_pattern

this will put the core dumps in /tmp, naming them "core". You can also add some modifiers to the content of the above, to customize the name of the core file, for example:

Code:

sudo echo /tmp/core.%u.%p > /proc/sys/kernel/core_pattern

will add the user ID of the owner of the process and the PID of the process itself. Other modifiers are available. See man 5 core for details.

colucix · 06-05-2008, 02:15 AM

Ah, just forgotten... by modifying a value under /proc you will lost changes upon reboot. To make them permanent, you can edit the file /etc/sysctl.conf, for example by adding the following lines

Code:

# Setup a directory to save core files into
kernel.core_pattern = /tmp/core

reakinator · 06-05-2008, 02:21 AM

Ah, thanks. "man 5 core" was the ticket.. heh.

regards,
Rich

reakinator · 06-11-2008, 04:05 AM

I've had a few core dumps since I made these changes, and they don't seem to be effecting the placement of core files.

I have "kernel.core_pattern = /tmp/core" in /etc/sysctl.conf, /proc/sys/kernel/core_pattern is: "|/usr/share/apport/apport "

I would really like to get these buggers in /tmp, as they are quite large.

colucix · 06-11-2008, 04:33 AM

Strange. If you did not reboot the machine after the modification of /etc/sysctl.conf, the change has not been applied. Have you manually modified the content of /proc/sys/kernel/core_pattern using the echo command?

Code:

sudo echo /tmp/core > /proc/sys/kernel/core_pattern

reakinator · 06-14-2008, 09:04 PM

yes this command does the trick (well, I have to su in, it doesn't work with sudo because of the > redirection thing), but as you said, it does not stick after a reboot.

"kernel.core_pattern = /tmp/core" doesn't seem to change this.