virt-edit(1)
NAME
virt-edit - Edit a file in a virtual machine
SYNOPSIS
virt-edit [--options] -d domname file [file ...]
virt-edit [--options] -a disk.img [-a disk.img ...] file [file ...]
virt-edit [-d domname|-a disk.img] file -e 'expr'
Old-style:
virt-edit domname file
virt-edit disk.img [disk.img ...] file
WARNING
Using "virt-edit" on live virtual machines, or concurrently with other disk editing tools, can be dangerous, potentially causing disk corruption. The virtual machine must be shut down before you use this command, and disk images must not be edited concurrently.
DESCRIPTION
"virt-edit" is a command line tool to edit "file" where each "file" exists in the named virtual machine (or disk image). Multiple filenames can be given, in which case they are each edited in turn. Each filename must be a full path, starting at the root directory (starting with '/'). If you want to just view a file, use virt-cat(1). For more complex cases you should look at the guestfish(1) tool (see "USING GUESTFISH" below). "virt-edit" cannot be used to create a new file. guestfish(1) can do that and much more.
EXAMPLES
Edit the named files interactively:
virt-edit -d mydomain /boot/grub/grub.conf
virt-edit -d mydomain /etc/passwd
For Windows guests, some Windows paths are understood:
virt-edit -d mywindomain 'c:
utoexec.bat'
If Perl is installed, you can also edit files non-interactively (see
"NON-INTERACTIVE EDITING" below). To change the init default level to
5:
virt-edit -d mydomain /etc/inittab -e 's/^id:.*/id:5:initdefault:/'
OPTIONS
--help
Display brief help.
-a file
--add file
Add file which should be a disk image from a virtual machine. If
the virtual machine has multiple block devices, you must supply all
of them with separate -a options.
The format of the disk image is auto-detected. To override this
and force a particular format use the --format=.. option.
-a URI
--add URI
Add a remote disk. See "ADDING REMOTE STORAGE" in guestfish(1).
-b extension
--backup extension
Create a backup of the original file in the guest disk image. The
backup has the original filename with "extension" added.
Usually the first character of "extension" would be a dot "." so
you would write:
virt-edit -b .orig [etc]
By default, no backup file is made.
-c URI
--connect URI
If using libvirt, connect to the given URI. If omitted, then we
connect to the default libvirt hypervisor.
If you specify guest block devices directly, then libvirt is not
used at all.
-d guest
--domain guest
Add all the disks from the named libvirt guest. Domain UUIDs can
be used instead of names.
--echo-keys
When prompting for keys and passphrases, virt-edit normally turns
echoing off so you cannot see what you are typing. If you are not
worried about Tempest attacks and there is no one else in the room
you can specify this flag to see what you are typing.
-e EXPR
--edit EXPR
--expr EXPR
Instead of launching the external editor, non-interactively apply
the Perl expression "EXPR" to each line in the file. See "NON-
INTERACTIVE EDITING" below.
Be careful to properly quote the expression to prevent it from
being altered by the shell.
Note that this option is only available when Perl 5 is installed.
--format=raw|qcow2|..
--format
The default for the -a option is to auto-detect the format of the
disk image. Using this forces the disk format for -a options which
follow on the command line. Using --format with no argument
switches back to auto-detection for subsequent -a options.
For example:
virt-edit --format=raw -a disk.img file
forces raw format (no auto-detection) for disk.img.
virt-edit --format=raw -a disk.img --format -a another.img file
forces raw format (no auto-detection) for disk.img and reverts to
auto-detection for another.img.
If you have untrusted raw-format guest disk images, you should use
this option to specify the disk format. This avoids a possible
security problem with malicious guests (CVE-2010-3851).
--keys-from-stdin
Read key or passphrase parameters from stdin. The default is to
try to read passphrases from the user by opening /dev/tty.
-m dev[:mountpoint[:options[:fstype]]]
--mount dev[:mountpoint[:options[:fstype]]]
Mount the named partition or logical volume on the given
mountpoint.
If the mountpoint is omitted, it defaults to /.
Specifying any mountpoint disables the inspection of the guest and
the mount of its root and all of its mountpoints, so make sure to
mount all the mountpoints needed to work with the filenames given
as arguments.
If you don't know what filesystems a disk image contains, you can
either run guestfish without this option, then list the partitions,
filesystems and LVs available (see "list-partitions", "list-
filesystems" and "lvs" commands), or you can use the
virt-filesystems(1) program.
The third (and rarely used) part of the mount parameter is the list
of mount options used to mount the underlying filesystem. If this
is not given, then the mount options are either the empty string or
"ro" (the latter if the --ro flag is used). By specifying the
mount options, you override this default choice. Probably the only
time you would use this is to enable ACLs and/or extended
attributes if the filesystem can support them:
-m /dev/sda1:/:acl,user_xattr
Using this flag is equivalent to using the "mount-options" command.
The fourth part of the parameter is the filesystem driver to use,
such as "ext3" or "ntfs". This is rarely needed, but can be useful
if multiple drivers are valid for a filesystem (eg: "ext2" and
"ext3"), or if libguestfs misidentifies a filesystem.
-v
--verbose
Enable verbose messages for debugging.
-V
--version
Display version number and exit.
-x Enable tracing of libguestfs API calls.
OLD-STYLE COMMAND LINE ARGUMENTS
Previous versions of virt-edit allowed you to write either:
virt-edit disk.img [disk.img ...] file
or
virt-edit guestname file
whereas in this version you should use -a or -d respectively to avoid
the confusing case where a disk image might have the same name as a
guest.
For compatibility the old style is still supported.
NON-INTERACTIVE EDITING
"virt-edit" normally calls out to $EDITOR (or vi) so the system administrator can interactively edit the file. There are two ways also to use "virt-edit" from scripts in order to make automated edits to files. (Note that although you can use "virt-edit" like this, it's less error-prone to write scripts directly using the libguestfs API and Augeas for configuration file editing.) The first method is to temporarily set $EDITOR to any script or program you want to run. The script is invoked as "$EDITOR tmpfile" and it should update "tmpfile" in place however it likes. The second method is to use the -e parameter of "virt-edit" to run a short Perl snippet in the style of sed(1). For example to replace all instances of "foo" with "bar" in a file: virt-edit -d domname filename -e 's/foo/bar/' The full power of Perl regular expressions can be used (see perlre(1)). For example to delete root's password you could do: virt-edit -d domname /etc/passwd -e 's/^root:.*?:/root::/' What really happens is that the snippet is evaluated as a Perl expression for each line of the file. The line, including the final "\n", is passed in $_ and the expression should update $_ or leave it unchanged. To delete a line, set $_ to the empty string. For example, to delete the "apache" user account from the password file you can do: virt-edit -d mydomain /etc/passwd -e '$_ = "" if /^apache:/' To insert a line, prepend or append it to $_. However appending lines to the end of the file is rather difficult this way since there is no concept of "last line of the file" - your expression just doesn't get called again. You might want to use the first method (setting $EDITOR) if you want to do this. The variable $lineno contains the current line number. As is traditional, the first line in the file is number 1. The return value from the expression is ignored, but the expression may call "die" in order to abort the whole program, leaving the original file untouched. Remember when matching the end of a line that $_ may contain the final "\n", or (for DOS files) "\r\n", or if the file does not end with a newline then neither of these. Thus to match or substitute some text at the end of a line, use this regular expression: /some text(\r?\n)?$/ Alternately, use the perl "chomp" function, being careful not to chomp $_ itself (since that would remove all newlines from the file): my $m = $_; chomp $m; $m =~ /some text$/
WINDOWS PATHS
"virt-edit" has a limited ability to understand Windows drive letters
and paths (eg. E:\foo ar.txt).
If and only if the guest is running Windows then:
* Drive letter prefixes like "C:" are resolved against the Windows
Registry to the correct filesystem.
* Any backslash ("\") characters in the path are replaced with
forward slashes so that libguestfs can process it.
* The path is resolved case insensitively to locate the file that
should be edited.
There are some known shortcomings:
* Some NTFS symbolic links may not be followed correctly.
* NTFS junction points that cross filesystems are not followed.
USING GUESTFISH
guestfish(1) is a more powerful, lower level tool which you can use when "virt-edit" doesn't work. Using "virt-edit" is approximately equivalent to doing: guestfish --rw -i -d domname edit /file where "domname" is the name of the libvirt guest, and /file is the full path to the file. The command above uses libguestfs's guest inspection feature and so does not work on guests that libguestfs cannot inspect, or on things like arbitrary disk images that don't contain guests. To edit a file on a disk image directly, use: guestfish --rw -a disk.img -m /dev/sda1 edit /file where disk.img is the disk image, /dev/sda1 is the filesystem within the disk image to edit, and /file is the full path to the file. "virt-edit" cannot create new files. Use the guestfish commands "touch", "write" or "upload" instead: guestfish --rw -i -d domname touch /newfile guestfish --rw -i -d domname write /newfile "new content" guestfish --rw -i -d domname upload localfile /newfile
ENVIRONMENT VARIABLES
"EDITOR"
If set, this string is used as the editor. It may contain
arguments, eg. "emacs -nw"
If not set, "vi" is used.
EXIT STATUS
This program returns 0 if successful, or non-zero if there was an error.
SEE ALSO
guestfs(3), guestfish(1), virt-cat(1), virt-copy-in(1), virt-tar-in(1), http://libguestfs.org/, perl(1), perlre(1).
AUTHOR
Richard W.M. Jones http://people.redhat.com/~rjones/
COPYRIGHT
Copyright (C) 2009-2016 Red Hat Inc.
LICENSE
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
BUGS
To get a list of bugs against libguestfs, use this link:
https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
To report a new bug against libguestfs, use this link:
https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
When reporting a bug, please supply:
* The version of libguestfs.
* Where you got libguestfs (eg. which Linux distro, compiled from
source, etc)
* Describe the bug accurately and give a way to reproduce it.
* Run libguestfs-test-tool(1) and paste the complete, unedited output
into the bug report.
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