Vmcore

In computing, a core dump, crash dump, memory dump, or system dump consists of the recorded state of the working memory of a computer program at a specific time, generally when the program has crashed or otherwise terminated abnormally. In practice, other key pieces of program state are usually dumped at the same time, including the processor registers, which may include the program counter and stack pointer, memory management information, and other processor and operating system flags and information. A snapshot dump (or snap dump) is a memory dump requested by the computer operator or by the running program, after which the program is able to continue. Core dumps are often used to assist in diagnosing and debugging errors in computer programs.

The name comes from magnetic core memory, the principal form of random access memory from the 1950s to the 1970s. The name has remained long after magnetic core technology became obsolete.

On many operating systems, a fatal error in a program automatically triggers a core dump; by extension the phrase "to dump core" has come to mean, in many cases, any fatal error, regardless of whether a record of the program memory results. The term "core dump", "memory dump", or just "dump" has also become a jargon to indicate any storing of a large amount of raw data for further examination or other purposes.

Earliest core dumps were paper printouts of the contents of memory, typically arranged in columns of octal or hexadecimal numbers (a "hex dump"), sometimes accompanied by their interpretations as machine language instructions, text strings, or decimal or floating-point numbers (cf. disassembler).

As memory sizes increased and post-mortem analysis utilities were developed, dumps were written to magnetic media like tape or disk.

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