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How to disable automatic core dumps in Debian 9?

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  How to disable automatic core dumps in Debian 9? Martin T <m4rtntns@gmail.com> - 2019-06-12 11:50 +0200
    Re: How to disable automatic core dumps in Debian 9? Reco <recoverym4n@enotuniq.net> - 2019-06-12 14:00 +0200
      Re: How to disable automatic core dumps in Debian 9? Martin T <m4rtntns@gmail.com> - 2019-06-12 16:20 +0200
        Re: How to disable automatic core dumps in Debian 9? Reco <recoverym4n@enotuniq.net> - 2019-06-12 16:40 +0200

#209834 — How to disable automatic core dumps in Debian 9?

Hi,

how to disable all automatic core dumps upon the process termination
in Debian 9? As Debian does not seem to use systemd-coredump, then I
set the "kernel.core_pattern=|/bin/false" kernel configuration in
sysctl.conf and following pam_limits.so module configuration:

$ grep -w core /etc/security/limits.conf
#        - core - limits the core file size (KB)
*               hard    core            0
root            hard    core            0
#root            hard    core            100000
$

When I execute a program, which crashes, then while the "core dumped"
is printed:

$ ./testprogram
Floating point exception (core dumped)
$

..then no actual core dump does not seem to be created.

Is the configuration above enough to disable core dumps or am I
missing something?

thanks,
Martin

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#209840

	Hi.

On Wed, Jun 12, 2019 at 12:49:14PM +0300, Martin T wrote:
> As Debian does not seem to use systemd-coredump,

It's a feature, not a flaw.


> then I set the "kernel.core_pattern=|/bin/false" kernel configuration
> in sysctl.conf

sysctl -w kernel.core_pattern=/dev/null

There's no need to pipe the core to /bin/false if you don't need the
core in the first place.


> and following pam_limits.so module configuration:
> 
> $ grep -w core /etc/security/limits.conf
> #        - core - limits the core file size (KB)
> *               hard    core            0
> root            hard    core            0
> #root            hard    core            100000
> $

rgrep core /etc/security/limits*

Would be more correct. Files at /etc/security/limits.d/ can override
limits.conf.


> Ween I execute a program, which crashes, then while the "core dumped"
> is printed:

A simple 'ulimit -c' would suffice.

Reco

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#209842

Reco,

thanks for reply!

> rgrep core /etc/security/limits*
> Would be more correct. Files at /etc/security/limits.d/ can override limits.conf.

Indeed. Output of "rgrep core /etc/security/limits*" is following:

$ rgrep core /etc/security/limits*
/etc/security/limits.conf:#        - core - limits the core file size (KB)
/etc/security/limits.conf:*               hard    core            0
/etc/security/limits.conf:root            hard    core            0
/etc/security/limits.conf:#root            hard    core            100000
$

So in short, the configuration in my initial e-mail was enough to
disable core dumps? After reading the "man 5 core", I also set the
"kernel.core_uses_pid" to 0.


thanks,
Martin

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#209843

	Hi.

On Wed, Jun 12, 2019 at 05:14:09PM +0300, Martin T wrote:
> Reco,
> 
> thanks for reply!
> 
> > rgrep core /etc/security/limits*
> > Would be more correct. Files at /etc/security/limits.d/ can override limits.conf.
> 
> Indeed. Output of "rgrep core /etc/security/limits*" is following:
> 
> $ rgrep core /etc/security/limits*
> /etc/security/limits.conf:#        - core - limits the core file size (KB)
> /etc/security/limits.conf:*               hard    core            0
> /etc/security/limits.conf:root            hard    core            0
> /etc/security/limits.conf:#root            hard    core            100000
> $
> 
> So in short, the configuration in my initial e-mail was enough to
> disable core dumps?

I prefer to do it this way, but that's a matter of a personal preference
(note that it works for root too):

*	-	core	0

Overriding kernel.core_pattern is way too limiting for me. I need those
core files in certain cases (but live happily without them by default).


> After reading the "man 5 core", I also set the "kernel.core_uses_pid" to 0.

Zero is a default value for this in Debian anyway. So - can't hurt, but
I doubt it'll change something for you.

Reco

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