How to dump core of an init spawned process

I am trying to force core dump of a program. Core dumping is enabled via

ulimit -c unlimited

If my program is launched by the init process, and I kill it like this

kill -6 <pid_of_prog>

I can't find the core.

However, if it is launched from a terminal, and I kill it with the above command, then it dumps core. The program chdir to 开发者_如何学运维a directory when it is launched, and the core file is found in this directory.

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ulimit does not set the limit of already launched process, so my init launched process is not affected by the ulimit command. I guess the correct answer is to use setrlimit