save a core dump of the operating system
[directory [device ...]]
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
in a selection of different human and machine readable formats. See
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
- 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
- Uncompress the dump in case it was compressed by the kernel.
- Print out some additional debugging information. Specify twice for more
- Compress the dump (see
The dump may already be compressed if the kernel was configured to do so
In this case, the option has no effect.
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
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
For kernel textdumps generated with the
facility, output will be stored in the
format and named
“#” 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 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.
savecore successfully copies the kernel
and the core dump, the core dump is cleared so that future invocations of
savecore will ignore it.
savecore utility is meant to be called
near the end of the initialization file /etc/rc (see
savecore utility appeared in
Support for kernel textdumps appeared in FreeBSD
The minfree code does not consider the effect of compression or sparse files.