xref: /freebsd/sbin/savecore/savecore.8 (revision 51e16cb8fc536913f490ac6bc9c17e92ebd0411b)

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.Dd April 4, 2022
.Dt SAVECORE 8
.Os
.Sh NAME
.Nm savecore
.Nd "save a core dump of the operating system"
.Sh SYNOPSIS
.Nm
.Fl c
.Op Fl v
.Op Ar device ...
.Nm
.Fl C
.Op Fl v
.Op Ar device ...
.Nm
.Fl L
.Op Fl fvZz
.Op Fl m Ar maxdumps
.Op Ar directory
.Nm
.Op Fl -libxo
.Op Fl fkuvz
.Op Fl m Ar maxdumps
.Op Ar directory Op Ar device ...
.Sh DESCRIPTION
The
.Nm
utility
copies a core dump into
.Ar directory ,
or the current working directory if no
.Ar directory
argument is given,
and enters a reboot message and information about the core dump into
the system log.
.Pp
The options are as follows:
.Bl -tag -width ".Fl m Ar maxdumps"
.It Fl -libxo
Generate output via
.Xr libxo 3
in a selection of different human and machine readable formats.
See
.Xr xo_parse_args 3
for details on command line arguments.
.It Fl 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
.Op Fl v
option.
.It Fl c
Clear the dump, so that future invocations of
.Nm
will ignore it.
.It Fl f
Force a dump to be taken even if either the dump was cleared or if the
dump header information is inconsistent.
.It Fl k
Do not clear the dump after saving it.
.It Fl L
Instruct
.Nm
to generate and save a kernel dump of the running system, rather than
copying one from a dump device.
.It Fl m Ar maxdumps
Maximum number of dumps to store.
Once the number of stored dumps is equal to
.Ar maxdumps
the counter will restart from
.Dv 0 .
.It Fl u
Uncompress the dump in case it was compressed by the kernel.
.It Fl v
Print out some additional debugging information.
Specify twice for more information.
.It Fl Z
Compress the dump (see
.Xr zstd 1 ) .
This option is only supported in conjunction with the
.Fl L
option.
Regular dumps can be configured for compression with zstd using
.Xr dumpon 8 .
.It Fl z
Compress the dump (see
.Xr gzip 1 ) .
The dump may already be compressed if the kernel was configured to
do so by
.Xr dumpon 8 .
In this case, the option has no effect.
.Pp
If used in conjunction with the
.Fl L
option, the requested live dump will be compressed with gzip.
.El
.Pp
The
.Nm
utility
looks for dumps on each device specified by the
.Ar device
argument(s), or on each device in
.Pa /etc/fstab
marked as
.Dq dump
or
.Dq swap .
The
.Nm
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
.Ar directory Ns Pa /vmcore.#
and information about the core in
.Ar directory Ns Pa /info.# .
If the core is encrypted, it saves the dump key in
.Ar directory Ns Pa /key.# .
The core can be later decrypted using
.Xr decryptcore 8 .
For kernel textdumps generated with the
.Xr textdump 4
facility, output will be stored in the
.Xr tar 5
format and named
.Ar directory Ns Pa /textdump.tar.# .
The
.Dq #
is the number from the first line of the file
.Ar directory Ns Pa /bounds ,
and it is incremented and stored back into the file each time
.Nm
successfully runs.
.Pp
The
.Nm
utility
also checks the available disk space before attempting to make the copies.
If there is insufficient disk space in the file system containing
.Ar directory ,
or if the file
.Ar directory Ns Pa /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.
.Pp
If
.Nm
successfully copies the kernel and the core dump, the core dump is cleared
so that future invocations of
.Nm
will ignore it.
.Pp
The
.Nm
utility
is meant to be called near the end of the initialization file
.Pa /etc/rc
(see
.Xr rc 8 ) .
.Sh SEE ALSO
.Xr gzip 1 ,
.Xr zstd 1 ,
.Xr getbootfile 3 ,
.Xr libxo 3 ,
.Xr xo_parse_args 3 ,
.Xr mem 4 ,
.Xr textdump 4 ,
.Xr tar 5 ,
.Xr crashinfo 8 ,
.Xr decryptcore 8 ,
.Xr dumpon 8 ,
.Xr syslogd 8
.Sh HISTORY
The
.Nm
utility appeared in
.Bx 4.1 .
.Pp
Support for kernel textdumps appeared in
.Fx 7.1 .
.Sh BUGS
The minfree code does not consider the effect of compression or sparse files.