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HP-UX 11i Version 3: February 2007

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core — format of core image file


The HP-UX system writes out a file containing a core image of a terminated process when certain signals are received (see signal(5) for the list of reasons). The most common causes are memory violations, illegal instructions, floating point exceptions, bus errors, and user-generated quit signals. The core image file is called core and is written in the process's working directory (provided it is allowed by normal access controls). A process with an effective user ID different from its real user ID does not produce a core image.

The file contains sufficient information to determine what the process was doing at the time of its termination. Core file contents consist of objects that represent different segments of a process. Each object is preceded by a corehead data structure, and each corehead data structure describes the corresponding object following it. The structure is defined in <sys/core.h>, and includes the following members:

int type; space_t space; caddr_t addr; size_t len;

The space and addr members specify the virtual memory address in the process where the described object began. The len member is the length of the object in bytes.

The following possible values for type are defined in <sys/core.h>:


Process data as it existed at the time the core image was created. This includes initialized data, uninitialized data, and the heap at the time the core image is generated.


A compiler-dependent data structure containing the exec data structure, the magic number of the executable file, and the command (see the declaration of the proc_exec structure in <sys/core.h>).


The version number of the core format produced. This number changes with each HP-UX release where the core format itself has changed. However, it does not necessarily change with every HP-UX release. CORE_FORMAT can thus be easily used by core-reading tools to determine whether they are compatible with a given core image. This type is expressed by a four-byte binary integer.


The null-terminated version string associated with the kernel at the time the core image was generated.


An architecture-dependent data structure containing per-process information such as hardware register contents. See the declaration of the proc_info structure in <sys/core.h>.


Process stack contents at the time the core image was created.

Objects dumped in a core image file are not arranged in any particular order. Use corehead information to determine the type of the object that immediately follows it.

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