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 --key "ID":clevis
120 Attempt passphrase-less unlocking for "ID" with Clevis, over
121 the network. Please refer to "ENCRYPTED DISKS" in guestfs(3)
122 for more information on network-bound disk encryption (NBDE).
123 Note that if any such option is present on the command line,
125 QEMU user networking will be automatically enabled for the
126 libguestfs appliance.
127 --keys-from-stdin
129 Read key or passphrase parameters from stdin. The default is to
130 try to read passphrases from the user by opening /dev/tty.
131 If there are multiple encrypted devices then you may need to supply
133 multiple keys on stdin, one per line.
134 -m dev[:mountpoint[:options[:fstype]]]
136 --mount dev[:mountpoint[:options[:fstype]]]
137 Mount the named partition or logical volume on the given
138 mountpoint.
139 If the mountpoint is omitted, it defaults to /.
141 Specifying any mountpoint disables the inspection of the guest and
143 the mount of its root and all of its mountpoints, so make sure to
144 mount all the mountpoints needed to work with the filenames given
145 as arguments.
146 If you don’t know what filesystems a disk image contains, you can
148 either run guestfish without this option, then list the partitions,
149 filesystems and LVs available (see "list-partitions", "list-
150 filesystems" and "lvs" commands), or you can use the
151 virt-filesystems(1) program.
152 The third (and rarely used) part of the mount parameter is the list
154 of mount options used to mount the underlying filesystem. If this
155 is not given, then the mount options are either the empty string or
156 "ro" (the latter if the --ro flag is used). By specifying the
157 mount options, you override this default choice. Probably the only
158 time you would use this is to enable ACLs and/or extended
159 attributes if the filesystem can support them:
160 -m /dev/sda1:/:acl,user_xattr
162 Using this flag is equivalent to using the "mount-options" command.
164 The fourth part of the parameter is the filesystem driver to use,
166 such as "ext3" or "ntfs". This is rarely needed, but can be useful
167 if multiple drivers are valid for a filesystem (eg: "ext2" and
168 "ext3"), or if libguestfs misidentifies a filesystem.
169 -v
171 --verbose
172 Enable verbose messages for debugging.
173 -V
175 --version
176 Display version number and exit.
177 -x Enable tracing of libguestfs API calls.
179
181 To list out the log files from guests, see the related tool
182 virt-log(1). It understands binary log formats such as the systemd
183 journal.
184
186 "virt-tail" has a limited ability to understand Windows drive letters
187 and paths (eg. E:\foo\bar.txt).
188 If and only if the guest is running Windows then:
190 • Drive letter prefixes like "C:" are resolved against the Windows
192 Registry to the correct filesystem.
193 • Any backslash ("\") characters in the path are replaced with
195 forward slashes so that libguestfs can process it.
196 • The path is resolved case insensitively to locate the file that
198 should be displayed.
199 There are some known shortcomings:
201 • Some NTFS symbolic links may not be followed correctly.
203 • NTFS junction points that cross filesystems are not followed.
205
207 This program returns 0 if successful, or non-zero if there was an
208 error.
209
211 guestfs(3), guestfish(1), virt-copy-out(1), virt-cat(1), virt-log(1),
212 virt-tar-out(1), tail(1), http://libguestfs.org/.
213
215 Richard W.M. Jones http://people.redhat.com/~rjones/
216
218 Copyright (C) 2016 Red Hat Inc.
219
221 This program is free software; you can redistribute it and/or modify it
222 under the terms of the GNU General Public License as published by the
223 Free Software Foundation; either version 2 of the License, or (at your
224 option) any later version.
225 This program is distributed in the hope that it will be useful, but
227 WITHOUT ANY WARRANTY; without even the implied warranty of
228 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
229 General Public License for more details.
230 You should have received a copy of the GNU General Public License along
232 with this program; if not, write to the Free Software Foundation, Inc.,
233 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
234
236 To get a list of bugs against libguestfs, use this link:
237 https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
238 To report a new bug against libguestfs, use this link:
240 https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
241 When reporting a bug, please supply:
243 • The version of libguestfs.
245 • Where you got libguestfs (eg. which Linux distro, compiled from
247 source, etc)
248 • Describe the bug accurately and give a way to reproduce it.
250 • Run libguestfs-test-tool(1) and paste the complete, unedited output
252 into the bug report.
253guestfs-tools-1.50.1 2023-04-06 virt-tail(1)