>Just got a note from a client saying that he had deleted a file called
>apache-1.2.4-van.core from a subdirectory on his Unix-based site. Can
>anyone tell me what this is and whether he has committed a fatal boo-boo?
i doubt it. from the name, it's probably a coredump trace.
there are various degrees of badness when a program running under unix
takes a dive. some of them happen without warning, and are so bad they
wedge the system. the ony way to solve those is with the three-finger
salute. others happen a little more slowly, and set off the kernel's
equivalent of a smoke detector before they can completely lock up the
machine.
when that happens, the kernel does an emergency shutdown on that particular
process, to save the rest of the system. as part of that shutdown
procedure, it takes a snapshot of the internal state of the program at the
moment the fault was detected.. contents of CPU registers, memory map,
program stack registers, the whole nine yards. that information is saved
as a file called a 'coredump', which, by convention, has the word 'core'
somewhere in its filename.
a coredump can be analyzed by a programmer with the appropriate tools, to
find out how & why the program went berserk. it's a sort of last-ditch
debugging aid. aside from that purpose, though, they're just the
smouldering ruins of crashed programs, strewn across the OS landscape.
not only is it okay to delete them, it's a good idea. if you don't, they
pile up and fill your drive. some BSD-based versions of unix even have a
program which scans the filesystem, automatically finding and deleting
coredumps that haven't been touched in N days.. it's called the GFR: Grim
File Reaper.
mike stone <[EMAIL PROTECTED]> 'net geek..
been there, done that, have network, will travel.
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