Core dumped but core file is not in the current directory

Question

While running a C program  It says   core dumped   but I can t see any files under the current path   I have set and verified the ulimit   ulimit -c unlimited  ulimit -a    I also tried to find a file named  core   but didn t get the core dumped file  Any help  where is my core file

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On recent Ubuntu  12 04 in my case   it s possible for  Segmentation fault  core dumped   to be printed  but no core file produced where you might expect one  for instance for a locally compiled program    This can happen if you have a core file size ulimit of 0  you haven t done ulimit -c unlimited  -- this is the default on Ubuntu  Normally that would suppress the   core dumped    cluing you into your mistake  but on Ubuntu  corefiles are piped to Apport  Ubuntu s crash reporting system  via  proc sys kernel core pattern  and this seems to cause the misleading message   If Apport discovers that the program in question is not one it should be reporting crashes for  which you can see happening in  var log apport log   it falls back to simulating the default kernel behaviour of putting a core file in the cwd  this is done in the script  usr share apport apport   This includes honouring ulimit  in which case it does nothing  But  I assume  as far as the kernel is concerned  a corefile was generated  and piped to apport   hence the message  Segmentation fault  core dumped     Ultimately PEBKAC for forgetting to set ulimit  but the misleading message had me thinking I was going mad for a while  wondering what was eating my corefiles    Also  in general  the core 5  manual page -- man 5 core -- is a good reference for where your core file ends up and reasons it might not be written

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Read  usr src linux Documentation sysctl kernel txt     proc sys kernel  core pattern is used to specify a core dumpfile pattern name   If the first character of the pattern is a      the kernel will treat the rest of the pattern as a command to run   The core dump will be written to the standard input of that program instead of to a file    Instead of writing the core dump to disk  your system is configured to send it to the abrt program instead   Automated Bug Reporting Tool is possibly not as documented as it should be    In any case  the quick answer is that you should be able to find your core file in  var cache abrt  where abrt stores it after being invoked   Similarly  other systems using Apport may squirrel away cores in  var crash  and so on

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I m on Linux Mint 19  Ubuntu 18 based   I wanted to have coredump files in current folder  I had to do two things    Change  proc sys kernel core pattern  by   echo  core  p  s  c  d  P  gt   proc sys kernel core pattern or by   sysctl -w kernel core pattern core  p  s  c  d  P  Raising limit for core file size by   ulimit -c unlimited   That was written already in the answers  but I wrote to summarize succinctly  Interestingly changing limit did not require root privileges  as per https   askubuntu com questions 162229 how-do-i-increase-the-open-files-limit-for-a-non-root-user non-root can only lower the limit  so that was unexpected - comments about it are welcome

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For fedora25  I could find core file at    var spool abrt ccpp-2017-02-16-16 36 51-2974 coredump   where ccpp-2017-02-16-16 36 51-2974  is pattern   s  c  p  u  g  t  P   as per   proc sys kernel core pattern

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If you re missing core dumps for binaries on RHEL and when using abrt  make sure that  etc abrt abrt-action-save-package-data conf  contains   ProcessUnpackaged   yes   This enables the creation of crash reports  including core dumps  for binaries which are not part of installed packages  e g  locally built

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I could think of two following possibilities    As others have already pointed out  the program might chdir    Is the user running the program allowed to write into the directory it chdir   ed to  If not  it cannot create the core dump  For some weird reason the core dump isn t named core   You can check  proc sys kernel core pattern for that  Also  the find command you named wouldn t find a typical core dump  You should use find   -name   core     as the typical name of the coredump is core  PID

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With the launch of systemd  there s another scenario aswell  By default systemd will store core dumps in its journal  being accessible with the systemd-coredumpctl command  Defined in the core pattern-file     cat  proc sys kernel core pattern    usr lib systemd systemd-coredump  p  u  g  s  t  e   This behaviour can be disabled with a simple  hack      ln -s  dev null  etc sysctl d 50-coredump conf   sysctl -w kernel core pattern core        or just reboot   As always  the size of core dumps has to be equal or higher than the size of the core that is being dumped  as done by for example ulimit -c unlimited

User · Answer

ulimit -c unlimited made the core file correctly appear in the current directory after a  core dumped

User · Answer

My efforts in WSL have been unsuccessful   For those running on Windows Subsystem for Linux  WSL  there seems to be an open issue at this time for missing core dump files   The comments indicate that      This is a known issue that we are aware of  it is something we are investigating    Github issue  Windows Developer Feedback

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If you use Fedora  in order to generate core dump file in the same directory of binary file  echo  quot core  e  p quot   gt   proc sys kernel core pattern  And ulimit -c unlimited

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In Ubuntu18 04  the most easist way to get a core file is inputing the command below to stop the apport service   sudo service apport stop   Then rerun the application  you will get dump file in current directory

User · Answer

Writing instructions to get a core dump under Ubuntu 16 04 LTS    As  jtn has mentioned in his answer  Ubuntu delegates the display of crashes to apport  which in turn refuses to write the dump because the program is not an installed package   To remedy the problem  we need to make sure apport writes core dump files for non-package programs as well  To do so  create a file named    config apport settings with the following contents   main  unpackaged true Now crash your program again  and see your crash files being generated within folder   var crash with names like   1000 crash  Note that these files cannot be read by gdb directly    Optional  To make the dumps readble by gdb  run the following command   apport-unpack  lt location of report gt   lt target directory gt    References  Core dump     Oracle VM VirtualBox

[c] Core dumped, but core file is not in the current directory?

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