How to generate core dump file in Ubuntu [duplicate]

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• How to generate a core dump in Linux on a segmentation fault? 12 answers

I would like to know how to generate a core dump file in Ubuntu. I am using Ubuntu 8.04.1 and gcc compiler 4.2.3. I have written a simple C program to generate a core dump. I have compiled the program as in -- gcc -g badpointer.c . When I run the program its gives segmentation fault but no core dump is generated. What additional things do i have to do to generate a core dump file ?