Ubuntu Manpage: virt-edit - Edit a file in a virtual machine

Provided by: guestfs-tools_1.52.0-2ubuntu5_amd64

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:\autoexec.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.

--blocksize=512
--blocksize=4096
--blocksize
This parameter sets the sector size of the disk image. It affects all explicitly added subsequent
disks after this parameter. Using --blocksize with no argument switches the disk sector size to the
default value which is usually 512 bytes. See also "guestfs_add_drive_opts" in guestfs(3).

-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).

--key SELECTOR
Specify a key for LUKS, to automatically open a LUKS device when using the inspection.

--key NAME:key:KEY_STRING
--key UUID:key:KEY_STRING
--key all:key:KEY_STRING
"NAME" is the libguestfs device name (eg. "/dev/sda1"). "UUID" is the device UUID. "all" means
try the key against any encrypted device.

Use the specified "KEY_STRING" as passphrase.

--key NAME:file:FILENAME
--key UUID:file:FILENAME
--key all:file:FILENAME
Read the passphrase from FILENAME.

--key NAME:clevis
--key UUID:clevis
--key all:clevis
Attempt passphrase-less unlocking for the device with Clevis, over the network. Please refer to
"ENCRYPTED DISKS" in guestfs(3) for more information on network-bound disk encryption (NBDE).

Note that if any such option is present on the command line, QEMU user networking will be
automatically enabled for the libguestfs appliance.

--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.

If there are multiple encrypted devices then you may need to supply multiple keys on stdin, one per
line.

-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\bar.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.

AUTHOR

       Richard W.M. Jones http://people.redhat.com/~rjones/

COPYRIGHT

       Copyright (C) 2009-2023 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.

guestfs-tools-1.52.0                               2024-04-01                                       virt-edit(1)