現在の debian 等ではデフォルトで、core ファイルを生成しない。
ulimit で設定を変える必要がある。(ulimit は shellの機能)
$ ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 15663 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 15663 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited
core file size のブロックサイズを 0 以外にすれば良い。
上記のテストコードでSEGVを発生させてみる。
$ gcc -o segv segv.c $ ./segv Segmentation fault
当然、core ファイルは生成されない。そこで、サイズを無制限にして実行
$ ulimit -c 0 $ ./segv Segmentation fault $ ulimit -c unlimited $ ./segv Segmentation fault (コアダンプ) $ gdb ./segv core GNU gdb (Debian 7.12-6) 7.12.0.20161007-git Copyright (C) 2016 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. Find the GDB manual and other documentation resources online at: <http://www.gnu.org/software/gdb/documentation/>. For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from ./segv...(no debugging symbols found)...done. [New LWP 2147] Core was generated by `./segv'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x000055bcc1e696b9 in main () (gdb) q $
なお、sshでログインした環境だと、2回目の実行に失敗することがあるので注意
$ ulimit -c unlimited -bash: ulimit: core file size: cannot modify limit: Operation not permitted