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

save a core dump of the operating system

savecore -c [-v] [device ...]

savecore -C [-v] [device ...]

savecore [--libxo] [-fkuvz] [-m maxdumps] [directory [device ...]]

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:

Generate output via libxo(3) in a selection of different human and machine readable formats. See xo_parse_args(3) for details on command line arguments.
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.
Clear the dump, so that future invocations of savecore will ignore it.
Force a dump to be taken even if either the dump was cleared or if the dump header information is inconsistent.
Do not clear the dump after saving it.
Maximum number of dumps to store. Once the number of stored dumps is equal to maxdumps the counter will restart from 0.
Uncompress the dump in case it was compressed by the kernel.
Print out some additional debugging information. Specify twice for more information.
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.

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)).

gzip(1), getbootfile(3), libxo(3), xo_parse_args(3), textdump(4), tar(5), crashinfo(8), decryptcore(8), dumpon(8), syslogd(8)

The savecore utility appeared in 4.1BSD.

Support for kernel textdumps appeared in FreeBSD 7.1.

The minfree code does not consider the effect of compression or sparse files.
November 17, 2020 FreeBSD 13.1-RELEASE

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