xref: /freebsd/sbin/savecore/savecore.8 (revision b0d29bc47dba79f6f38e67eabadfb4b32ffd9390)
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28.\"     From: @(#)savecore.8	8.1 (Berkeley) 6/5/93
29.\" $FreeBSD$
30.\"
31.Dd March 17, 2018
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 fkvz
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 v
96Print out some additional debugging information.
97Specify twice for more information.
98.It Fl z
99Compress the dump (see
100.Xr gzip 1 ) .
101The dump may already be compressed if the kernel was configured to
102do so by
103.Xr dumpon 8 .
104In this case, the option has no effect.
105.El
106.Pp
107The
108.Nm
109utility
110looks for dumps on each device specified by the
111.Ar device
112argument(s), or on each device in
113.Pa /etc/fstab
114marked as
115.Dq dump
116or
117.Dq swap .
118The
119.Nm
120utility
121checks the core dump in various ways to make sure that it is complete.
122If it passes these checks, it saves the core image in
123.Ar directory Ns Pa /vmcore.#
124and information about the core in
125.Ar directory Ns Pa /info.# .
126If the core is encrypted, it saves the dump key in
127.Ar directory Ns Pa /key.# .
128The core can be later decrypted using
129.Xr decryptcore 8 .
130For kernel textdumps generated with the
131.Xr textdump 4
132facility, output will be stored in the
133.Xr tar 5
134format and named
135.Ar directory Ns Pa /textdump.tar.# .
136The
137.Dq #
138is the number from the first line of the file
139.Ar directory Ns Pa /bounds ,
140and it is incremented and stored back into the file each time
141.Nm
142successfully runs.
143.Pp
144The
145.Nm
146utility
147also checks the available disk space before attempting to make the copies.
148If there is insufficient disk space in the file system containing
149.Ar directory ,
150or if the file
151.Ar directory Ns Pa /minfree
152exists and the number of free kilobytes (for non-superusers) in the
153file system after the copies were made would be less than the number
154in the first line of this file, the copies are not attempted.
155.Pp
156If
157.Nm
158successfully copies the kernel and the core dump, the core dump is cleared
159so that future invocations of
160.Nm
161will ignore it.
162.Pp
163The
164.Nm
165utility
166is meant to be called near the end of the initialization file
167.Pa /etc/rc
168(see
169.Xr rc 8 ) .
170.Sh SEE ALSO
171.Xr gzip 1 ,
172.Xr getbootfile 3 ,
173.Xr libxo 3 ,
174.Xr xo_parse_args 3 ,
175.Xr textdump 4 ,
176.Xr tar 5 ,
177.Xr crashinfo 8 ,
178.Xr decryptcore 8 ,
179.Xr dumpon 8 ,
180.Xr syslogd 8
181.Sh HISTORY
182The
183.Nm
184utility appeared in
185.Bx 4.1 .
186.Pp
187Support for kernel textdumps appeared in
188.Fx 7.1 .
189.Sh BUGS
190The minfree code does not consider the effect of compression or sparse files.
191