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 -m dev[:mountpoint[:options[:fstype]]]
124 --mount dev[:mountpoint[:options[:fstype]]]
125 Mount the named partition or logical volume on the given
126 mountpoint.
127 If the mountpoint is omitted, it defaults to /.
129 Specifying any mountpoint disables the inspection of the guest and
131 the mount of its root and all of its mountpoints, so make sure to
132 mount all the mountpoints needed to work with the filenames given
133 as arguments.
134 If you don’t know what filesystems a disk image contains, you can
136 either run guestfish without this option, then list the partitions,
137 filesystems and LVs available (see "list-partitions", "list-
138 filesystems" and "lvs" commands), or you can use the
139 virt-filesystems(1) program.
140 The third (and rarely used) part of the mount parameter is the list
142 of mount options used to mount the underlying filesystem. If this
143 is not given, then the mount options are either the empty string or
144 "ro" (the latter if the --ro flag is used). By specifying the
145 mount options, you override this default choice. Probably the only
146 time you would use this is to enable ACLs and/or extended
147 attributes if the filesystem can support them:
148 -m /dev/sda1:/:acl,user_xattr
150 Using this flag is equivalent to using the "mount-options" command.
152 The fourth part of the parameter is the filesystem driver to use,
154 such as "ext3" or "ntfs". This is rarely needed, but can be useful
155 if multiple drivers are valid for a filesystem (eg: "ext2" and
156 "ext3"), or if libguestfs misidentifies a filesystem.
157 -v
159 --verbose
160 Enable verbose messages for debugging.
161 -V
163 --version
164 Display version number and exit.
165 -x Enable tracing of libguestfs API calls.
167
169 To list out the log files from guests, see the related tool
170 virt-log(1). It understands binary log formats such as the systemd
171 journal.
172
174 "virt-tail" has a limited ability to understand Windows drive letters
175 and paths (eg. E:\foo\bar.txt).
176 If and only if the guest is running Windows then:
178 · Drive letter prefixes like "C:" are resolved against the Windows
180 Registry to the correct filesystem.
181 · Any backslash ("\") characters in the path are replaced with
183 forward slashes so that libguestfs can process it.
184 · The path is resolved case insensitively to locate the file that
186 should be displayed.
187 There are some known shortcomings:
189 · Some NTFS symbolic links may not be followed correctly.
191 · NTFS junction points that cross filesystems are not followed.
193
195 This program returns 0 if successful, or non-zero if there was an
196 error.
197
199 guestfs(3), guestfish(1), virt-copy-out(1), virt-cat(1), virt-log(1),
200 virt-tar-out(1), tail(1), http://libguestfs.org/.
201
203 Richard W.M. Jones http://people.redhat.com/~rjones/
204
206 Copyright (C) 2016 Red Hat Inc.
207
209 This program is free software; you can redistribute it and/or modify it
210 under the terms of the GNU General Public License as published by the
211 Free Software Foundation; either version 2 of the License, or (at your
212 option) any later version.
213 This program is distributed in the hope that it will be useful, but
215 WITHOUT ANY WARRANTY; without even the implied warranty of
216 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
217 General Public License for more details.
218 You should have received a copy of the GNU General Public License along
220 with this program; if not, write to the Free Software Foundation, Inc.,
221 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
222
224 To get a list of bugs against libguestfs, use this link:
225 https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
226 To report a new bug against libguestfs, use this link:
228 https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
229 When reporting a bug, please supply:
231 · The version of libguestfs.
233 · Where you got libguestfs (eg. which Linux distro, compiled from
235 source, etc)
236 · Describe the bug accurately and give a way to reproduce it.
238 · Run libguestfs-test-tool(1) and paste the complete, unedited output
240 into the bug report.
241libguestfs-1.42.0 2020-03-09 virt-tail(1)