1virt-tail(1) Virtualization Support virt-tail(1)
2
6 virt-tail - Follow (tail) files in a virtual machine
7
9 virt-tail [--options] -d domname file [file ...]
10 virt-tail [--options] -a disk.img [-a disk.img ...] file [file ...]
12
14 "virt-tail" is a command line tool to follow (tail) the contents of
15 "file" where "file" exists in the named virtual machine (or disk
16 image). It is similar to the ordinary command "tail -f".
17 Multiple filenames can be given, in which case each is followed
19 separately. Each filename must be a full path, starting at the root
20 directory (starting with '/').
21 The command keeps running until:
23 • The user presses the ^C or an interrupt signal is received.
25 • None of the listed files was found in the guest, or they all get
27 deleted.
28 • There is an unrecoverable error.
30
32 Follow /var/log/messages inside a virtual machine called "mydomain":
33 virt-tail -d mydomain /var/log/messages
35
37 --help
38 Display brief help.
39 -a file
41 --add file
42 Add file which should be a disk image from a virtual machine. If
43 the virtual machine has multiple block devices, you must supply all
44 of them with separate -a options.
45 The format of the disk image is auto-detected. To override this
47 and force a particular format use the --format=.. option.
48 -a URI
50 --add URI
51 Add a remote disk. See "ADDING REMOTE STORAGE" in guestfish(1).
52 --blocksize=512
54 --blocksize=4096
55 --blocksize
56 This parameter sets the sector size of the disk image. It affects
57 all explicitly added subsequent disks after this parameter. Using
58 --blocksize with no argument switches the disk sector size to the
59 default value which is usually 512 bytes. See also
60 "guestfs_add_drive_opts" in guestfs(3).
61 -c URI
63 --connect URI
64 If using libvirt, connect to the given URI. If omitted, then we
65 connect to the default libvirt hypervisor.
66 If you specify guest block devices directly (-a), then libvirt is
68 not used at all.
69 -d guest
71 --domain guest
72 Add all the disks from the named libvirt guest. Domain UUIDs can
73 be used instead of names.
74 --echo-keys
76 When prompting for keys and passphrases, virt-tail normally turns
77 echoing off so you cannot see what you are typing. If you are not
78 worried about Tempest attacks and there is no one else in the room
79 you can specify this flag to see what you are typing.
80 -f
82 --follow
83 This option is ignored. virt-tail always behaves like tail(1) -f.
84 You don't need to specify the -f option.
85 --format=raw|qcow2|..
87 --format
88 The default for the -a option is to auto-detect the format of the
89 disk image. Using this forces the disk format for -a options which
90 follow on the command line. Using --format with no argument
91 switches back to auto-detection for subsequent -a options.
92 For example:
94 virt-tail --format=raw -a disk.img file
96 forces raw format (no auto-detection) for disk.img.
98 virt-tail --format=raw -a disk.img --format -a another.img file
100 forces raw format (no auto-detection) for disk.img and reverts to
102 auto-detection for another.img.
103 If you have untrusted raw-format guest disk images, you should use
105 this option to specify the disk format. This avoids a possible
106 security problem with malicious guests (CVE-2010-3851).
107 --key SELECTOR
109 Specify a key for LUKS, to automatically open a LUKS device when
110 using the inspection. "ID" can be either the libguestfs device
111 name, or the UUID of the LUKS device.
112 --key "ID":key:KEY_STRING
114 Use the specified "KEY_STRING" as passphrase.
115 --key "ID":file:FILENAME
117 Read the passphrase from FILENAME.
118 --keys-from-stdin
120 Read key or passphrase parameters from stdin. The default is to
121 try to read passphrases from the user by opening /dev/tty.
122 If there are multiple encrypted devices then you may need to supply
124 multiple keys on stdin, one per line.
125 -m dev[:mountpoint[:options[:fstype]]]
127 --mount dev[:mountpoint[:options[:fstype]]]
128 Mount the named partition or logical volume on the given
129 mountpoint.
130 If the mountpoint is omitted, it defaults to /.
132 Specifying any mountpoint disables the inspection of the guest and
134 the mount of its root and all of its mountpoints, so make sure to
135 mount all the mountpoints needed to work with the filenames given
136 as arguments.
137 If you don’t know what filesystems a disk image contains, you can
139 either run guestfish without this option, then list the partitions,
140 filesystems and LVs available (see "list-partitions", "list-
141 filesystems" and "lvs" commands), or you can use the
142 virt-filesystems(1) program.
143 The third (and rarely used) part of the mount parameter is the list
145 of mount options used to mount the underlying filesystem. If this
146 is not given, then the mount options are either the empty string or
147 "ro" (the latter if the --ro flag is used). By specifying the
148 mount options, you override this default choice. Probably the only
149 time you would use this is to enable ACLs and/or extended
150 attributes if the filesystem can support them:
151 -m /dev/sda1:/:acl,user_xattr
153 Using this flag is equivalent to using the "mount-options" command.
155 The fourth part of the parameter is the filesystem driver to use,
157 such as "ext3" or "ntfs". This is rarely needed, but can be useful
158 if multiple drivers are valid for a filesystem (eg: "ext2" and
159 "ext3"), or if libguestfs misidentifies a filesystem.
160 -v
162 --verbose
163 Enable verbose messages for debugging.
164 -V
166 --version
167 Display version number and exit.
168 -x Enable tracing of libguestfs API calls.
170
172 To list out the log files from guests, see the related tool
173 virt-log(1). It understands binary log formats such as the systemd
174 journal.
175
177 "virt-tail" has a limited ability to understand Windows drive letters
178 and paths (eg. E:\foo\bar.txt).
179 If and only if the guest is running Windows then:
181 • Drive letter prefixes like "C:" are resolved against the Windows
183 Registry to the correct filesystem.
184 • Any backslash ("\") characters in the path are replaced with
186 forward slashes so that libguestfs can process it.
187 • The path is resolved case insensitively to locate the file that
189 should be displayed.
190 There are some known shortcomings:
192 • Some NTFS symbolic links may not be followed correctly.
194 • NTFS junction points that cross filesystems are not followed.
196
198 This program returns 0 if successful, or non-zero if there was an
199 error.
200
202 guestfs(3), guestfish(1), virt-copy-out(1), virt-cat(1), virt-log(1),
203 virt-tar-out(1), tail(1), http://libguestfs.org/.
204
206 Richard W.M. Jones http://people.redhat.com/~rjones/
207
209 Copyright (C) 2016 Red Hat Inc.
210
212 This program is free software; you can redistribute it and/or modify it
213 under the terms of the GNU General Public License as published by the
214 Free Software Foundation; either version 2 of the License, or (at your
215 option) any later version.
216 This program is distributed in the hope that it will be useful, but
218 WITHOUT ANY WARRANTY; without even the implied warranty of
219 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
220 General Public License for more details.
221 You should have received a copy of the GNU General Public License along
223 with this program; if not, write to the Free Software Foundation, Inc.,
224 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
225
227 To get a list of bugs against libguestfs, use this link:
228 https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
229 To report a new bug against libguestfs, use this link:
231 https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
232 When reporting a bug, please supply:
234 • The version of libguestfs.
236 • Where you got libguestfs (eg. which Linux distro, compiled from
238 source, etc)
239 • Describe the bug accurately and give a way to reproduce it.
241 • Run libguestfs-test-tool(1) and paste the complete, unedited output
243 into the bug report.
244guestfs-tools-1.47.2 2021-07-22 virt-tail(1)