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

NAME
     savecore -- save a core dump of the operating system

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

DESCRIPTION
     When the NetBSD kernel encounters a fatal error, the panic(9) routine
     arranges 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,
     including 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
     http://www.netbsd.org/, or using send-pr(1), containing as much
     information as possible about the circumstances of the crash.  Since
     crash dumps are typically very large and may contain whatever
     (potentially confidential) 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 somewhere 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
                invocations of savecore will ignore it.

     -f         Forces a dump to be taken even if the dump doesn't appear
                correct 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
                information 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
     successfully runs.

     savecore also checks the available disk space before attempting to make
     the copies.  If there is insufficient disk space in the file system
     containing 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.

SEE ALSO
     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)

HISTORY
     The savecore command appeared in 4.1BSD.

BUGS
     The minfree code does not consider the effect of compression.

NetBSD 6.1.5                  September 13, 2011                  NetBSD 6.1.5