Controlling core files (Linux)

Controlling core files (Linux)

core file文件重定位：echo /tmp/core.%e.%p > /proc/sys/kernel/core_pattern

 

Core files get created when a program misbehaves due to a bug, or a violation of the cpu or memory protection mechanisms. The operating system kills the program and creates the core file.

If you don't want core files at all, set "ulimit -c 0" in your startup files. That's the default on many systems; in /etc/profile you may find 

 
ulimit -S -c 0 > /dev/null 2>&1 
 

If you DO want core files, you need to reset that in your own .bash_profile:

 
ulimit -c 50000 
 

would allow core files but limit them to 50,000 bytes.

You have more control of core files in /proc/sys/kernel/

For example, you can do eliminate the tagged on pid by

 
echo "0" > /proc/sys/kernel/core_uses_pid 
 

Core files will then just be named "core". People do things like that so that a user can choose to put a non-writable file named "core" in directories where they don't want to generate core dumps. That could be a directory (mkdir core) or a file (touch core;chmod 000 core). I've seen it suggested that a symlink named core would redirect the dump to wherever it pointed, but I found that didn't work.

But perhaps more interesting is that you can do: 

mkdir /tmp/corefiles 
chmod 777 /tmp/corefiles 
echo "/tmp/corefiles/core" > /proc/sys/kernel/core_pattern 
 

All corefiles then get tossed to /tmp/corefiles (don't change core_uses_pid if you do this).

Test this with a simple script:

 
# script that dumps core 
kill -s SIGSEGV $$