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SAVECORE(8)		  BSD System Manager's Manual		   SAVECORE(8)

     savecore -- save a	core dump of the operating system

     savecore [-fvz] [-N system] [-Z level] [directory]
     savecore -c [-v] [-N system]
     savecore -n [-v] [-N system]

     When the NetBSD kernel encounters a fatal error, the panic(9) routine ar-
     ranges for	a snapshot of the contents of physical memory to be written
     into a dump area, typically in the	swap partition.

     Upon a subsequent reboot, savecore	is typically run out of	rc(8), before
     swapping is enabled, to copy the kernel and the saved memory image	into
     directory,	and enters a reboot message and	information about the core
     dump into the system log.	If a directory is not specified, then
     /var/crash	is used.

     The kernel	and core file can then be analyzed using various tools,	in-
     cluding crash(8), dmesg(8), fstat(1), gdb(1), iostat(8), netstat(1),
     ps(1), and	pstat(8), to attempt to	deduce the cause of the	crash.

     Crashes are usually the result of hardware	faults or kernel bugs.	If a
     kernel bug	is suspected, a	full bug report	should be filed	at, or	using send-pr(1), containing as	much informa-
     tion as possible about the	circumstances of the crash.  Since crash dumps
     are typically very	large and may contain whatever (potentially confiden-
     tial) information was in memory at	the time of the	crash, do NOT include
     a copy of the crash dump file in the bug report; instead, save it some-
     where in the event	that a NetBSD developer	wants to examine it.

     The options are as	follows:

     -c		Only clears the	dump without saving it,	so that	future invoca-
		tions of savecore will ignore it.

     -f		Forces a dump to be taken even if the dump doesn't appear cor-
		rect or	there is insufficient disk space.

     -n		Check whether a	dump is	present	without	taking further action.
		The command exits with zero status if a	dump is	present, or
		with non-zero status otherwise.

     -N		Use system as the kernel instead of the	default	(returned by
		getbootfile(3)).  Note that getbootfile(3) uses	secure_path(3)
		to check that kernel file is "secure" and will default to
		/netbsd	if the check fails.

     -v		Prints out some	additional debugging information.

     -z		Compresses the core dump and kernel (see gzip(1)).

     -Z	level	Set the	compression level for -z to level.  Defaults to	1 (the
		fastest	compression mode).  Refer to gzip(1) for more informa-
		tion regarding the compression level.

     savecore checks the core dump in various ways to make sure	that it	is
     current and that it corresponds to	the currently running system.  If it
     passes these checks, it saves the core image in directory/netbsd.#.core
     and the system in directory/netbsd.# (or in directory/netbsd.#.core.gz
     and directory/netbsd.#.gz,	respectively, if the -z	option is used).  The
     "#" is the	number from the	first line of the file directory/bounds, and
     it	is incremented and stored back into the	file each time savecore	suc-
     cessfully runs.

     savecore also checks the available	disk space before attempting to	make
     the copies.  If there is insufficient disk	space in the file system con-
     taining directory,	or if the file directory/minfree exists	and the	number
     of	free kilobytes (for non-superusers) in the file	system after the
     copies were made would be less than the number in the first line of this
     file, the copies are not attempted.

     If	savecore successfully copies the kernel	and the	core dump, the core
     dump is cleared so	that future invocations	of savecore will ignore	it.

     fstat(1), gdb(1), gzip(1),	netstat(1), ps(1), send-pr(1), crash(8),
     dmesg(8), iostat(8), pstat(8), rc(8), syslogd(8), panic(9)

     The savecore command appeared in 4.1BSD.

     The minfree code does not consider	the effect of compression.

BSD			      September	13, 2011			   BSD


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