1virt-cat(1)                 Virtualization Support                 virt-cat(1)
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3
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NAME

6       virt-cat - Display files in a virtual machine
7

SYNOPSIS

9        virt-cat [--options] -d domname file [file ...]
10
11        virt-cat [--options] -a disk.img [-a disk.img ...] file [file ...]
12
13       Old-style:
14
15        virt-cat domname file
16
17        virt-cat disk.img file
18

DESCRIPTION

20       "virt-cat" is a command line tool to display the contents of "file"
21       where "file" exists in the named virtual machine (or disk image).
22
23       Multiple filenames can be given, in which case they are concatenated
24       together.  Each filename must be a full path, starting at the root
25       directory (starting with '/').
26
27       "virt-cat" can be used to quickly view a file.  To edit a file, use
28       "virt-edit".  For more complex cases you should look at the
29       guestfish(1) tool (see "USING GUESTFISH" below).
30

EXAMPLES

32       Display /etc/fstab file from inside the libvirt VM called "mydomain":
33
34        virt-cat -d mydomain /etc/fstab
35
36       Find out what packages were recently installed:
37
38        virt-cat -d mydomain /var/log/yum.log | tail
39
40       Find out who is logged on inside a virtual machine:
41
42        virt-cat -d mydomain /var/run/utmp > /tmp/utmp
43        who /tmp/utmp
44
45       or who was logged on:
46
47        virt-cat -d mydomain /var/log/wtmp > /tmp/wtmp
48        last -f /tmp/wtmp
49

OPTIONS

51       --help
52           Display brief help.
53
54       -a file
55       --add file
56           Add file which should be a disk image from a virtual machine.  If
57           the virtual machine has multiple block devices, you must supply all
58           of them with separate -a options.
59
60           The format of the disk image is auto-detected.  To override this
61           and force a particular format use the --format=.. option.
62
63       -a URI
64       --add URI
65           Add a remote disk.  See "ADDING REMOTE STORAGE" in guestfish(1).
66
67       --blocksize=512
68       --blocksize=4096
69       --blocksize
70           This parameter sets the sector size of the disk image.  It affects
71           all explicitly added subsequent disks after this parameter.  Using
72           --blocksize with no argument switches the disk sector size to the
73           default value which is usually 512 bytes.  See also
74           "guestfs_add_drive_opts" in guestfs(3).
75
76       -c URI
77       --connect URI
78           If using libvirt, connect to the given URI.  If omitted, then we
79           connect to the default libvirt hypervisor.
80
81           If you specify guest block devices directly (-a), then libvirt is
82           not used at all.
83
84       -d guest
85       --domain guest
86           Add all the disks from the named libvirt guest.  Domain UUIDs can
87           be used instead of names.
88
89       --echo-keys
90           When prompting for keys and passphrases, virt-cat normally turns
91           echoing off so you cannot see what you are typing.  If you are not
92           worried about Tempest attacks and there is no one else in the room
93           you can specify this flag to see what you are typing.
94
95       --format=raw|qcow2|..
96       --format
97           The default for the -a option is to auto-detect the format of the
98           disk image.  Using this forces the disk format for -a options which
99           follow on the command line.  Using --format with no argument
100           switches back to auto-detection for subsequent -a options.
101
102           For example:
103
104            virt-cat --format=raw -a disk.img file
105
106           forces raw format (no auto-detection) for disk.img.
107
108            virt-cat --format=raw -a disk.img --format -a another.img file
109
110           forces raw format (no auto-detection) for disk.img and reverts to
111           auto-detection for another.img.
112
113           If you have untrusted raw-format guest disk images, you should use
114           this option to specify the disk format.  This avoids a possible
115           security problem with malicious guests (CVE-2010-3851).
116
117       --key SELECTOR
118           Specify a key for LUKS, to automatically open a LUKS device when
119           using the inspection.  "ID" can be either the libguestfs device
120           name, or the UUID of the LUKS device.
121
122           --key "ID":key:KEY_STRING
123               Use the specified "KEY_STRING" as passphrase.
124
125           --key "ID":file:FILENAME
126               Read the passphrase from FILENAME.
127
128           --key "ID":clevis
129               Attempt passphrase-less unlocking for "ID" with Clevis, over
130               the network.  Please refer to "ENCRYPTED DISKS" in guestfs(3)
131               for more information on network-bound disk encryption (NBDE).
132
133               Note that if any such option is present on the command line,
134               QEMU user networking will be automatically enabled for the
135               libguestfs appliance.
136
137       --keys-from-stdin
138           Read key or passphrase parameters from stdin.  The default is to
139           try to read passphrases from the user by opening /dev/tty.
140
141           If there are multiple encrypted devices then you may need to supply
142           multiple keys on stdin, one per line.
143
144       -m dev[:mountpoint[:options[:fstype]]]
145       --mount dev[:mountpoint[:options[:fstype]]]
146           Mount the named partition or logical volume on the given
147           mountpoint.
148
149           If the mountpoint is omitted, it defaults to /.
150
151           Specifying any mountpoint disables the inspection of the guest and
152           the mount of its root and all of its mountpoints, so make sure to
153           mount all the mountpoints needed to work with the filenames given
154           as arguments.
155
156           If you don’t know what filesystems a disk image contains, you can
157           either run guestfish without this option, then list the partitions,
158           filesystems and LVs available (see "list-partitions", "list-
159           filesystems" and "lvs" commands), or you can use the
160           virt-filesystems(1) program.
161
162           The third (and rarely used) part of the mount parameter is the list
163           of mount options used to mount the underlying filesystem.  If this
164           is not given, then the mount options are either the empty string or
165           "ro" (the latter if the --ro flag is used).  By specifying the
166           mount options, you override this default choice.  Probably the only
167           time you would use this is to enable ACLs and/or extended
168           attributes if the filesystem can support them:
169
170            -m /dev/sda1:/:acl,user_xattr
171
172           Using this flag is equivalent to using the "mount-options" command.
173
174           The fourth part of the parameter is the filesystem driver to use,
175           such as "ext3" or "ntfs". This is rarely needed, but can be useful
176           if multiple drivers are valid for a filesystem (eg: "ext2" and
177           "ext3"), or if libguestfs misidentifies a filesystem.
178
179       -v
180       --verbose
181           Enable verbose messages for debugging.
182
183       -V
184       --version
185           Display version number and exit.
186
187       -x  Enable tracing of libguestfs API calls.
188

OLD-STYLE COMMAND LINE ARGUMENTS

190       Previous versions of virt-cat allowed you to write either:
191
192        virt-cat disk.img [disk.img ...] file
193
194       or
195
196        virt-cat guestname file
197
198       whereas in this version you should use -a or -d respectively to avoid
199       the confusing case where a disk image might have the same name as a
200       guest.
201
202       For compatibility the old style is still supported.
203

LOG FILES

205       To list out the log files from guests, see the related tool
206       virt-log(1).  It understands binary log formats such as the systemd
207       journal.
208
209       To follow (tail) text log files, use virt-tail(1).
210

WINDOWS PATHS

212       "virt-cat" has a limited ability to understand Windows drive letters
213       and paths (eg. E:\foo\bar.txt).
214
215       If and only if the guest is running Windows then:
216
217       •   Drive letter prefixes like "C:" are resolved against the Windows
218           Registry to the correct filesystem.
219
220       •   Any backslash ("\") characters in the path are replaced with
221           forward slashes so that libguestfs can process it.
222
223       •   The path is resolved case insensitively to locate the file that
224           should be displayed.
225
226       There are some known shortcomings:
227
228       •   Some NTFS symbolic links may not be followed correctly.
229
230       •   NTFS junction points that cross filesystems are not followed.
231

USING GUESTFISH

233       guestfish(1) is a more powerful, lower level tool which you can use
234       when "virt-cat" doesn't work.
235
236       Using "virt-cat" is approximately equivalent to doing:
237
238        guestfish --ro -i -d domname download file -
239
240       where "domname" is the name of the libvirt guest, and "file" is the
241       full path to the file.  Note the final "-" (meaning "output to
242       stdout").
243
244       The command above uses libguestfs’s guest inspection feature and so
245       does not work on guests that libguestfs cannot inspect, or on things
246       like arbitrary disk images that don't contain guests.  To display a
247       file from a disk image directly, use:
248
249        guestfish --ro -a disk.img -m /dev/sda1 download file -
250
251       where disk.img is the disk image, /dev/sda1 is the filesystem within
252       the disk image, and "file" is the full path to the file.
253

EXIT STATUS

255       This program returns 0 if successful, or non-zero if there was an
256       error.
257

SEE ALSO

259       guestfs(3), guestfish(1), virt-copy-out(1), virt-edit(1), virt-log(1),
260       virt-tail(1), virt-tar-out(1), http://libguestfs.org/.
261

AUTHOR

263       Richard W.M. Jones http://people.redhat.com/~rjones/
264
266       Copyright (C) 2010-2023 Red Hat Inc.
267

LICENSE

269       This program is free software; you can redistribute it and/or modify it
270       under the terms of the GNU General Public License as published by the
271       Free Software Foundation; either version 2 of the License, or (at your
272       option) any later version.
273
274       This program is distributed in the hope that it will be useful, but
275       WITHOUT ANY WARRANTY; without even the implied warranty of
276       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
277       General Public License for more details.
278
279       You should have received a copy of the GNU General Public License along
280       with this program; if not, write to the Free Software Foundation, Inc.,
281       51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
282

BUGS

284       To get a list of bugs against libguestfs, use this link:
285       https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
286
287       To report a new bug against libguestfs, use this link:
288       https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
289
290       When reporting a bug, please supply:
291
292       •   The version of libguestfs.
293
294       •   Where you got libguestfs (eg. which Linux distro, compiled from
295           source, etc)
296
297       •   Describe the bug accurately and give a way to reproduce it.
298
299       •   Run libguestfs-test-tool(1) and paste the complete, unedited output
300           into the bug report.
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303
304guestfs-tools-1.50.1              2023-04-06                       virt-cat(1)
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