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

Provided by: libguestfs-tools_1.40.2-7ubuntu5_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.

-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. "SELECTOR"
can be in one of the following formats:

--key "DEVICE":key:KEY_STRING
Use the specified "KEY_STRING" as passphrase.

--key "DEVICE":file:FILENAME
Read the passphrase from FILENAME.

--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\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) 2009-2019 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.

libguestfs-1.40.2                                  2019-02-07                                       virt-edit(1)