How do I enable core dumps for everybody

Overview

In most Linux Distributions core file creation is disabled by default for a normal user. However, it can be necessary to enable this feature for an application (e.g. Oracle). For example, if you encounter an ORA-7445
error in Oracle, then it must be possible to write a core file for the user
«oracle».

To enable writing core files you use the ulimit command, it controls the resources available to a process started by the shell, on systems that allow such control.

If you try to enable writing core files, usually you run in the following problem. Normally SSH is used to logon to the server.

ssh oracle@ora-server

$ ulimit -a
core file size (blocks, -c) 0

data seg size (kbytes, -d) unlimited

file size (blocks, -f) unlimited

pending signals (-i) 1024

max locked memory (kbytes, -l) 32

max memory size (kbytes, -m) unlimited

open files (-n) 65536

pipe size (512 bytes, -p) 8

POSIX message queues (bytes, -q) 819200

stack size (kbytes, -s) 10240

cpu time (seconds, -t) unlimited

max user processes (-u) 16384

virtual memory (kbytes, -v) unlimited

file locks (-x) unlimited
Now, try (not as user root)to change the core file size to unlimited

$ ulimit -S -c unlimited

-bash: ulimit: core file size: cannot modify limit: Operation not permitted

Solution

Check Environment for ulimit

The first step is to check, that you don't set ulimit -c 0 in any shell configuration files for this user, for example in$HOME/.bash_profile or$HOME/.bashrc.
Uncomment it if you have such an entry.

#

# Do not produce core dumps

#

# ulimit -c 0


Globally enable Core Dumps

This must be done as user root, usually in
/etc/security/limits.conf

# /etc/security/limits.conf

#

#Each line describes a limit for a user in the form:

#

# <domain> <type> <item> <value>

#

* soft core unlimited

Logoff and Logon again and set ulimit

ssh oracle@ora-server

$ ulimit -c

0Try to set the limit as user root first

su -

ulimit -c unlimited

ulimit -c

unlimited

Now you can set ulimit also for user oracle

su - oracle

ulimit -c unlimited

ulimit -c

unlimited

Perhaps the last step number 3 is not necessary, but we have figured out, that this is the way which always work. The core file size limitation is usually also set in different configuration files. If you want to enable cores, you can
uncomment them.

In /etc/profile (Redhat)

# No core files by default

# ulimit -S -c 0 > /dev/null 2>&1
In /etc/init.d/functions (Redhat)

# make sure it doesn't core dump anywhere unless requested

# ulimit -S -c ${DAEMON_COREFILE_LIMIT:-0} >/dev/null 2>&1
Now, from this current shell you can generate the core, so checkulimit before.

$ ulimit -a
core file size (blocks, -c) unlimited

data seg size (kbytes, -d) unlimited

file size (blocks, -f) unlimited

pending signals (-i) 1024

max locked memory (kbytes, -l) 32

max memory size (kbytes, -m) unlimited

open files (-n) 65536

pipe size (512 bytes, -p) 8

POSIX message queues (bytes, -q) 819200

stack size (kbytes, -s) 10240

cpu time (seconds, -t) unlimited

max user processes (-u) 16384

virtual memory (kbytes, -v) unlimited

file locks (-x) unlimited