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 -c URI
54 --connect URI
55 If using libvirt, connect to the given URI. If omitted, then we
56 connect to the default libvirt hypervisor.
57 If you specify guest block devices directly (-a), then libvirt is
59 not used at all.
60 -d guest
62 --domain guest
63 Add all the disks from the named libvirt guest. Domain UUIDs can
64 be used instead of names.
65 --echo-keys
67 When prompting for keys and passphrases, virt-tail normally turns
68 echoing off so you cannot see what you are typing. If you are not
69 worried about Tempest attacks and there is no one else in the room
70 you can specify this flag to see what you are typing.
71 -f
73 --follow
74 This option is ignored. virt-tail always behaves like tail(1) -f.
75 You don't need to specify the -f option.
76 --format=raw|qcow2|..
78 --format
79 The default for the -a option is to auto-detect the format of the
80 disk image. Using this forces the disk format for -a options which
81 follow on the command line. Using --format with no argument
82 switches back to auto-detection for subsequent -a options.
83 For example:
85 virt-tail --format=raw -a disk.img file
87 forces raw format (no auto-detection) for disk.img.
89 virt-tail --format=raw -a disk.img --format -a another.img file
91 forces raw format (no auto-detection) for disk.img and reverts to
93 auto-detection for another.img.
94 If you have untrusted raw-format guest disk images, you should use
96 this option to specify the disk format. This avoids a possible
97 security problem with malicious guests (CVE-2010-3851).
98 --key SELECTOR
100 Specify a key for LUKS, to automatically open a LUKS device when
101 using the inspection. "SELECTOR" can be in one of the following
102 formats:
103 --key "DEVICE":key:KEY_STRING
105 Use the specified "KEY_STRING" as passphrase.
106 --key "DEVICE":file:FILENAME
108 Read the passphrase from FILENAME.
109 --keys-from-stdin
111 Read key or passphrase parameters from stdin. The default is to
112 try to read passphrases from the user by opening /dev/tty.
113 -m dev[:mountpoint[:options[:fstype]]]
115 --mount dev[:mountpoint[:options[:fstype]]]
116 Mount the named partition or logical volume on the given
117 mountpoint.
118 If the mountpoint is omitted, it defaults to /.
120 Specifying any mountpoint disables the inspection of the guest and
122 the mount of its root and all of its mountpoints, so make sure to
123 mount all the mountpoints needed to work with the filenames given
124 as arguments.
125 If you don’t know what filesystems a disk image contains, you can
127 either run guestfish without this option, then list the partitions,
128 filesystems and LVs available (see "list-partitions", "list-
129 filesystems" and "lvs" commands), or you can use the
130 virt-filesystems(1) program.
131 The third (and rarely used) part of the mount parameter is the list
133 of mount options used to mount the underlying filesystem. If this
134 is not given, then the mount options are either the empty string or
135 "ro" (the latter if the --ro flag is used). By specifying the
136 mount options, you override this default choice. Probably the only
137 time you would use this is to enable ACLs and/or extended
138 attributes if the filesystem can support them:
139 -m /dev/sda1:/:acl,user_xattr
141 Using this flag is equivalent to using the "mount-options" command.
143 The fourth part of the parameter is the filesystem driver to use,
145 such as "ext3" or "ntfs". This is rarely needed, but can be useful
146 if multiple drivers are valid for a filesystem (eg: "ext2" and
147 "ext3"), or if libguestfs misidentifies a filesystem.
148 -v
150 --verbose
151 Enable verbose messages for debugging.
152 -V
154 --version
155 Display version number and exit.
156 -x Enable tracing of libguestfs API calls.
158
160 To list out the log files from guests, see the related tool
161 virt-log(1). It understands binary log formats such as the systemd
162 journal.
163
165 "virt-tail" has a limited ability to understand Windows drive letters
166 and paths (eg. E:\foo\bar.txt).
167 If and only if the guest is running Windows then:
169 · Drive letter prefixes like "C:" are resolved against the Windows
171 Registry to the correct filesystem.
172 · Any backslash ("\") characters in the path are replaced with
174 forward slashes so that libguestfs can process it.
175 · The path is resolved case insensitively to locate the file that
177 should be displayed.
178 There are some known shortcomings:
180 · Some NTFS symbolic links may not be followed correctly.
182 · NTFS junction points that cross filesystems are not followed.
184
186 This program returns 0 if successful, or non-zero if there was an
187 error.
188
190 guestfs(3), guestfish(1), virt-copy-out(1), virt-cat(1), virt-log(1),
191 virt-tar-out(1), tail(1), http://libguestfs.org/.
192
194 Richard W.M. Jones http://people.redhat.com/~rjones/
195
197 Copyright (C) 2016 Red Hat Inc.
198
200 This program is free software; you can redistribute it and/or modify it
201 under the terms of the GNU General Public License as published by the
202 Free Software Foundation; either version 2 of the License, or (at your
203 option) any later version.
204 This program is distributed in the hope that it will be useful, but
206 WITHOUT ANY WARRANTY; without even the implied warranty of
207 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
208 General Public License for more details.
209 You should have received a copy of the GNU General Public License along
211 with this program; if not, write to the Free Software Foundation, Inc.,
212 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
213
215 To get a list of bugs against libguestfs, use this link:
216 https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
217 To report a new bug against libguestfs, use this link:
219 https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
220 When reporting a bug, please supply:
222 · The version of libguestfs.
224 · Where you got libguestfs (eg. which Linux distro, compiled from
226 source, etc)
227 · Describe the bug accurately and give a way to reproduce it.
229 · Run libguestfs-test-tool(1) and paste the complete, unedited output
231 into the bug report.
232libguestfs-1.40.1 2019-01-17 virt-tail(1)