SAVECORE(8) FreeBSD System Manager's Manual SAVECORE(8)
NAME
savecore - save a core dump of the operating system
SYNOPSIS
savecore -c [-v] [device ...]
savecore -C [-v] [device ...]
savecore -L [-fvZz] [-m maxdumps] [directory]
savecore [--libxo] [-fkuvz] [-m maxdumps] [directory [device ...]]
DESCRIPTION
The savecore utility copies a core dump into directory, or the current
working directory if no directory argument is given, and enters a reboot
message and information about the core dump into the system log.
The options are as follows:
--libxo Generate output via libxo(3) in a selection of different
human and machine readable formats. See xo_options(7) for
details on command line arguments.
-C Check to see if a dump exists, and display a brief message
to indicate the status. An exit status of 0 indicates
that a dump is there, 1 indicates that none exists. This
option is compatible only with the [-v] option.
-c Clear the dump, so that future invocations of savecore
will ignore it.
-f Force a dump to be taken even if either the dump was
cleared or if the dump header information is inconsistent.
-k Do not clear the dump after saving it.
-L Instruct savecore to generate and save a kernel dump of
the running system, rather than copying one from a dump
device.
-m maxdumps Maximum number of dumps to store. Once the number of
stored dumps is equal to maxdumps the counter will restart
from 0.
-u Uncompress the dump in case it was compressed by the
kernel.
-v Print out some additional debugging information. Specify
twice for more information.
-Z Compress the dump (see zstd(1)). This option is only
supported in conjunction with the -L option. Regular
dumps can be configured for compression with zstd using
dumpon(8).
-z Compress the dump (see gzip(1)). The dump may already be
compressed if the kernel was configured to do so by
dumpon(8). In this case, the option has no effect.
If used in conjunction with the -L option, the requested
live dump will be compressed with gzip.
The savecore utility looks for dumps on each device specified by the
device argument(s), or on each device in /etc/fstab marked as "dump" or
"swap". The savecore utility checks the core dump in various ways to
make sure that it is complete. If it passes these checks, it saves the
core image in directory/vmcore.# and information about the core in
directory/info.#. If the core is encrypted, it saves the dump key in
directory/key.#. The core can be later decrypted using decryptcore(8).
For kernel textdumps generated with the textdump(4) facility, output will
be stored in the tar(5) format and named directory/textdump.tar.#. 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.
The savecore utility 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.
The savecore utility is meant to be called near the end of the
initialization file /etc/rc (see rc(8)).
SEE ALSO
gzip(1), zstd(1), getbootfile(3), libxo(3), xo_options(7), mem(4),
textdump(4), tar(5), crashinfo(8), decryptcore(8), dumpon(8), syslogd(8)
HISTORY
The savecore utility appeared in 4.1BSD.
Support for kernel textdumps appeared in FreeBSD 7.1.
BUGS
The minfree code does not consider the effect of compression or sparse
files.
FreeBSD 15.1-STABLE-HBSD July 16, 2025 SAVECORE(8)