xref: /freebsd/sbin/savecore/savecore.8 (revision 5bb3134a8c21cb87b30e135ef168483f0333dabb)
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28.\"     From: @(#)savecore.8	8.1 (Berkeley) 6/5/93
29.\" $FreeBSD$
30.\"
31.Dd November 17, 2020
32.Dt SAVECORE 8
33.Os
34.Sh NAME
35.Nm savecore
36.Nd "save a core dump of the operating system"
37.Sh SYNOPSIS
38.Nm
39.Fl c
40.Op Fl v
41.Op Ar device ...
42.Nm
43.Fl C
44.Op Fl v
45.Op Ar device ...
46.Nm
47.Op Fl -libxo
48.Op Fl fkuvz
49.Op Fl m Ar maxdumps
50.Op Ar directory Op Ar device ...
51.Sh DESCRIPTION
52The
53.Nm
54utility
55copies a core dump into
56.Ar directory ,
57or the current working directory if no
58.Ar directory
59argument is given,
60and enters a reboot message and information about the core dump into
61the system log.
62.Pp
63The options are as follows:
64.Bl -tag -width ".Fl m Ar maxdumps"
65.It Fl -libxo
66Generate output via
67.Xr libxo 3
68in a selection of different human and machine readable formats.
69See
70.Xr xo_parse_args 3
71for details on command line arguments.
72.It Fl C
73Check to see if a dump exists,
74and display a brief message to indicate the status.
75An exit status of 0 indicates that a dump is there,
761 indicates that none exists.
77This option is compatible only with the
78.Op Fl v
79option.
80.It Fl c
81Clear the dump, so that future invocations of
82.Nm
83will ignore it.
84.It Fl f
85Force a dump to be taken even if either the dump was cleared or if the
86dump header information is inconsistent.
87.It Fl k
88Do not clear the dump after saving it.
89.It Fl m Ar maxdumps
90Maximum number of dumps to store.
91Once the number of stored dumps is equal to
92.Ar maxdumps
93the counter will restart from
94.Dv 0 .
95.It Fl u
96Uncompress the dump in case it was compressed by the kernel.
97.It Fl v
98Print out some additional debugging information.
99Specify twice for more information.
100.It Fl z
101Compress the dump (see
102.Xr gzip 1 ) .
103The dump may already be compressed if the kernel was configured to
104do so by
105.Xr dumpon 8 .
106In this case, the option has no effect.
107.El
108.Pp
109The
110.Nm
111utility
112looks for dumps on each device specified by the
113.Ar device
114argument(s), or on each device in
115.Pa /etc/fstab
116marked as
117.Dq dump
118or
119.Dq swap .
120The
121.Nm
122utility
123checks the core dump in various ways to make sure that it is complete.
124If it passes these checks, it saves the core image in
125.Ar directory Ns Pa /vmcore.#
126and information about the core in
127.Ar directory Ns Pa /info.# .
128If the core is encrypted, it saves the dump key in
129.Ar directory Ns Pa /key.# .
130The core can be later decrypted using
131.Xr decryptcore 8 .
132For kernel textdumps generated with the
133.Xr textdump 4
134facility, output will be stored in the
135.Xr tar 5
136format and named
137.Ar directory Ns Pa /textdump.tar.# .
138The
139.Dq #
140is the number from the first line of the file
141.Ar directory Ns Pa /bounds ,
142and it is incremented and stored back into the file each time
143.Nm
144successfully runs.
145.Pp
146The
147.Nm
148utility
149also checks the available disk space before attempting to make the copies.
150If there is insufficient disk space in the file system containing
151.Ar directory ,
152or if the file
153.Ar directory Ns Pa /minfree
154exists and the number of free kilobytes (for non-superusers) in the
155file system after the copies were made would be less than the number
156in the first line of this file, the copies are not attempted.
157.Pp
158If
159.Nm
160successfully copies the kernel and the core dump, the core dump is cleared
161so that future invocations of
162.Nm
163will ignore it.
164.Pp
165The
166.Nm
167utility
168is meant to be called near the end of the initialization file
169.Pa /etc/rc
170(see
171.Xr rc 8 ) .
172.Sh SEE ALSO
173.Xr gzip 1 ,
174.Xr getbootfile 3 ,
175.Xr libxo 3 ,
176.Xr xo_parse_args 3 ,
177.Xr textdump 4 ,
178.Xr tar 5 ,
179.Xr crashinfo 8 ,
180.Xr decryptcore 8 ,
181.Xr dumpon 8 ,
182.Xr syslogd 8
183.Sh HISTORY
184The
185.Nm
186utility appeared in
187.Bx 4.1 .
188.Pp
189Support for kernel textdumps appeared in
190.Fx 7.1 .
191.Sh BUGS
192The minfree code does not consider the effect of compression or sparse files.
193