bc7ed46b63
kernel during dump time. A real life scenario is that cores are compressed to reduce size of dumpon partition, but we either don't care about space in the /var/crash or we have a filesystem level compression of /var/crash. And we want cores to be uncompressed in /var/crash because we'd like to instantily read them with kgdb. In this case we want kernel to write cores compressed, but savecore(1) write them uncompressed. Reviewed by: markj, gallatin Relnotes: yes Differential Revision: https://reviews.freebsd.org/D27245
193 lines
5.2 KiB
Groff
193 lines
5.2 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" From: @(#)savecore.8 8.1 (Berkeley) 6/5/93
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.\" $FreeBSD$
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.\"
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.Dd November 17, 2020
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.Dt SAVECORE 8
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.Os
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.Sh NAME
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.Nm savecore
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.Nd "save a core dump of the operating system"
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.Sh SYNOPSIS
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.Nm
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.Fl c
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.Op Fl v
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.Op Ar device ...
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.Nm
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.Fl C
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.Op Fl v
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.Op Ar device ...
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.Nm
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.Op Fl -libxo
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.Op Fl fkuvz
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.Op Fl m Ar maxdumps
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.Op Ar directory Op Ar device ...
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.Sh DESCRIPTION
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The
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.Nm
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utility
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copies a core dump into
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.Ar directory ,
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or the current working directory if no
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.Ar directory
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argument is given,
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and enters a reboot message and information about the core dump into
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the system log.
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.Pp
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The options are as follows:
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.Bl -tag -width ".Fl m Ar maxdumps"
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.It Fl -libxo
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Generate output via
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.Xr libxo 3
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in a selection of different human and machine readable formats.
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See
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.Xr xo_parse_args 3
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for details on command line arguments.
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.It Fl C
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Check to see if a dump exists,
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and display a brief message to indicate the status.
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An exit status of 0 indicates that a dump is there,
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1 indicates that none exists.
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This option is compatible only with the
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.Op Fl v
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option.
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.It Fl c
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Clear the dump, so that future invocations of
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.Nm
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will ignore it.
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.It Fl f
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Force a dump to be taken even if either the dump was cleared or if the
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dump header information is inconsistent.
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.It Fl k
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Do not clear the dump after saving it.
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.It Fl m Ar maxdumps
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Maximum number of dumps to store.
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Once the number of stored dumps is equal to
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.Ar maxdumps
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the counter will restart from
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.Dv 0 .
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.It Fl u
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Uncompress the dump in case it was compressed by the kernel.
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.It Fl v
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Print out some additional debugging information.
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Specify twice for more information.
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.It Fl z
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Compress the dump (see
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.Xr gzip 1 ) .
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The dump may already be compressed if the kernel was configured to
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do so by
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.Xr dumpon 8 .
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In this case, the option has no effect.
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.El
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.Pp
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The
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.Nm
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utility
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looks for dumps on each device specified by the
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.Ar device
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argument(s), or on each device in
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.Pa /etc/fstab
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marked as
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.Dq dump
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or
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.Dq swap .
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The
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.Nm
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utility
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checks the core dump in various ways to make sure that it is complete.
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If it passes these checks, it saves the core image in
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.Ar directory Ns Pa /vmcore.#
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and information about the core in
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.Ar directory Ns Pa /info.# .
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If the core is encrypted, it saves the dump key in
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.Ar directory Ns Pa /key.# .
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The core can be later decrypted using
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.Xr decryptcore 8 .
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For kernel textdumps generated with the
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.Xr textdump 4
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facility, output will be stored in the
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.Xr tar 5
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format and named
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.Ar directory Ns Pa /textdump.tar.# .
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The
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.Dq #
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is the number from the first line of the file
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.Ar directory Ns Pa /bounds ,
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and it is incremented and stored back into the file each time
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.Nm
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successfully runs.
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.Pp
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The
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.Nm
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utility
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also checks the available disk space before attempting to make the copies.
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If there is insufficient disk space in the file system containing
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.Ar directory ,
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or if the file
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.Ar directory Ns Pa /minfree
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exists and the number of free kilobytes (for non-superusers) in the
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file system after the copies were made would be less than the number
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in the first line of this file, the copies are not attempted.
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.Pp
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If
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.Nm
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successfully copies the kernel and the core dump, the core dump is cleared
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so that future invocations of
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.Nm
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will ignore it.
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.Pp
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The
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.Nm
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utility
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is meant to be called near the end of the initialization file
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.Pa /etc/rc
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(see
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.Xr rc 8 ) .
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.Sh SEE ALSO
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.Xr gzip 1 ,
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.Xr getbootfile 3 ,
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.Xr libxo 3 ,
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.Xr xo_parse_args 3 ,
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.Xr textdump 4 ,
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.Xr tar 5 ,
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.Xr crashinfo 8 ,
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.Xr decryptcore 8 ,
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.Xr dumpon 8 ,
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.Xr syslogd 8
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Bx 4.1 .
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.Pp
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Support for kernel textdumps appeared in
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.Fx 7.1 .
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.Sh BUGS
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The minfree code does not consider the effect of compression or sparse files.
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