generator: Use Continuation Passing Style (CPS) in output_to function.

[libguestfs.git] / guestfish.pod

=encoding utf8

=head1 NAME

guestfish - the libguestfs Filesystem Interactive SHell

=head1 SYNOPSIS

 guestfish [--options] [commands]

 guestfish

 guestfish -a disk.img

 guestfish -a disk.img -m dev[:mountpoint]

 guestfish -i libvirt-domain

 guestfish -i disk.img [disk.img ...]

=head1 EXAMPLES

=head2 As an interactive shell

 $ guestfish
 
 Welcome to guestfish, the libguestfs filesystem interactive shell for
 editing virtual machine filesystems.
 
 Type: 'help' for help with commands
       'quit' to quit the shell
 
 ><fs> help

=head2 From shell scripts

Create a new C</etc/motd> file in a guest:

 guestfish <<_EOF_
 add disk.img
 run
 mount /dev/vg_guest/lv_root /
 write_file /etc/motd "Welcome, new users" 0
 _EOF_

List the LVM logical volumes in a guest:

 guestfish -a disk.img --ro <<_EOF_
 run
 lvs
 _EOF_

=head2 On one command line

Update C</etc/resolv.conf> in a guest:

 guestfish \
   add disk.img : run : mount /dev/vg_guest/lv_root / : \
   write-file /etc/resolv.conf "nameserver 1.2.3.4" 0

Edit C</boot/grub/grub.conf> interactively:

 guestfish --add disk.img \
   --mount /dev/vg_guest/lv_root \
   --mount /dev/sda1:/boot \
   edit /boot/grub/grub.conf

=head2 Using virt-inspector

Use the I<-i> option to get virt-inspector to mount
the filesystems automatically as they would be mounted
in the virtual machine:

 guestfish --ro -i disk.img cat /etc/group

=head2 As a script interpreter

Create a 50MB disk containing an ext2-formatted partition:

 #!/usr/bin/guestfish -f
 alloc /tmp/output.img 50M
 run
 part-disk /dev/sda mbr
 mkfs ext2 /dev/sda1

=head2 Remote control

 eval `guestfish --listen --ro`
 guestfish --remote add disk.img
 guestfish --remote run
 guestfish --remote lvs

=head1 DESCRIPTION

Guestfish is a shell and command-line tool for examining and modifying
virtual machine filesystems.  It uses libguestfs and exposes all of
the functionality of the guestfs API, see L<guestfs(3)>.

Guestfish gives you structured access to the libguestfs API, from
shell scripts or the command line or interactively.  If you want to
rescue a broken virtual machine image, you might want to look at the
L<virt-rescue(1)> command.

Using guestfish in read/write mode on live virtual machines can be
dangerous, potentially causing disk corruption.  Use the I<--ro>
(read-only) option to use guestfish safely if the disk image or
virtual machine might be live.

=head1 OPTIONS

=over 4

=item B<--help>

Displays general help on options.

=item B<-h> | B<--cmd-help>

Lists all available guestfish commands.

=item B<-h cmd> | B<--cmd-help cmd>

Displays detailed help on a single command C<cmd>.

=item B<-a image> | B<--add image>

Add a block device or virtual machine image to the shell.

=item B<-D> | B<--no-dest-paths>

Don't tab-complete paths on the guest filesystem.  It is useful to be
able to hit the tab key to complete paths on the guest filesystem, but
this causes extra "hidden" guestfs calls to be made, so this option is
here to allow this feature to be disabled.

=item B<-f file> | B<--file file>

Read commands from C<file>.  To write pure guestfish
scripts, use:

 #!/usr/bin/guestfish -f

=item B<-i> | B<--inspector>

Run virt-inspector on the named libvirt domain or list of disk
images.  If virt-inspector is available and if it can identify
the domain or disk images, then partitions will be mounted
correctly at start-up.

Typical usage is either:

 guestfish -i myguest

(for an inactive libvirt domain called I<myguest>), or:

 guestfish --ro -i myguest

(for active domains, readonly), or specify the block device directly:

 guestfish -i /dev/Guests/MyGuest

You cannot use I<-a>, I<-m>, I<--listen>, I<--remote> or I<--selinux>
in conjunction with this option, and options other than I<--ro> might
not behave correctly.

See also: L<virt-inspector(1)>.

=item B<--listen>

Fork into the background and listen for remote commands.  See section
I<REMOTE CONTROL GUESTFISH OVER A SOCKET> below.

=item B<-m dev[:mountpoint]> | B<--mount dev[:mountpoint]>

Mount the named partition or logical volume on the given mountpoint.

If the mountpoint is omitted, it defaults to C</>.

You have to mount something on C</> before most commands will work.

If any C<-m> or C<--mount> options are given, the guest is
automatically launched.

If you don't know what filesystems a disk image contains, you
can either run guestfish without this option, then list the partitions
and LVs available (see L</list-partitions> and L</lvs> commands),
or you can use the L<virt-list-filesystems(1)> program.

=item B<-n> | B<--no-sync>

Disable autosync.  This is enabled by default.  See the discussion
of autosync in the L<guestfs(3)> manpage.

=item B<--remote[=pid]>

Send remote commands to C<$GUESTFISH_PID> or C<pid>.  See section
I<REMOTE CONTROL GUESTFISH OVER A SOCKET> below.

=item B<-r> | B<--ro>

This changes the C<-a> and C<-m> options so that disks are added and
mounts are done read-only (see L<guestfs(3)/guestfs_mount_ro>).

The option must always be used if the disk image or virtual machine
might be running, and is generally recommended in cases where you
don't need write access to the disk.

=item B<--selinux>

Enable SELinux support for the guest.  See L<guestfs(3)/SELINUX>.

=item B<-v> | B<--verbose>

Enable very verbose messages.  This is particularly useful if you find
a bug.

=item B<-V> | B<--version>

Display the guestfish / libguestfs version number and exit.

=item B<-x>

Echo each command before executing it.

=back

=head1 COMMANDS ON COMMAND LINE

Any additional (non-option) arguments are treated as commands to
execute.

Commands to execute should be separated by a colon (C<:>), where the
colon is a separate parameter.  Thus:

 guestfish cmd [args...] : cmd [args...] : cmd [args...] ...

If there are no additional arguments, then we enter a shell, either an
interactive shell with a prompt (if the input is a terminal) or a
non-interactive shell.

In either command line mode or non-interactive shell, the first
command that gives an error causes the whole shell to exit.  In
interactive mode (with a prompt) if a command fails, you can continue
to enter commands.

=head1 USING launch (OR run)

As with L<guestfs(3)>, you must first configure your guest by adding
disks, then launch it, then mount any disks you need, and finally
issue actions/commands.  So the general order of the day is:

=over 4

=item *

add or -a/--add

=item *

launch (aka run)

=item *

mount or -m/--mount

=item *

any other commands

=back

C<run> is a synonym for C<launch>.  You must C<launch> (or C<run>)
your guest before mounting or performing any other commands.

The only exception is that if the C<-m> or C<--mount> option was
given, the guest is automatically run for you (simply because
guestfish can't mount the disks you asked for without doing this).

=head1 QUOTING

You can quote ordinary parameters using either single or double
quotes.  For example:

 add "file with a space.img"

 rm '/file name'

 rm '/"'

A few commands require a list of strings to be passed.  For these, use
a whitespace-separated list, enclosed in quotes.  Strings containing whitespace
to be passed through must be enclosed in single quotes.  A literal single quote
must be escaped with a backslash.

 vgcreate VG "/dev/sda1 /dev/sdb1"
 command "/bin/echo 'foo      bar'"
 command "/bin/echo \'foo\'"

=head1 WILDCARDS AND GLOBBING

Neither guestfish nor the underlying guestfs API performs
wildcard expansion (globbing) by default.  So for example the
following will not do what you expect:

 rm-rf /home/*

Assuming you don't have a directory literally called C</home/*>
then the above command will return an error.

To perform wildcard expansion, use the C<glob> command.

 glob rm-rf /home/*

runs C<rm-rf> on each path that matches (ie. potentially running
the command many times), equivalent to:

 rm-rf /home/jim
 rm-rf /home/joe
 rm-rf /home/mary

C<glob> only works on simple guest paths and not on device names.

If you have several parameters, each containing a wildcard, then glob
will perform a cartesian product.

=head1 COMMENTS

Any line which starts with a I<#> character is treated as a comment
and ignored.  The I<#> can optionally be preceeded by whitespace,
but B<not> by a command.  For example:

 # this is a comment
         # this is a comment
 foo # NOT a comment

Blank lines are also ignored.

=head1 RUNNING COMMANDS LOCALLY

Any line which starts with a I<!> character is treated as a command
sent to the local shell (C</bin/sh> or whatever L<system(3)> uses).
For example:

 !mkdir local
 tgz-out /remote local/remote-data.tar.gz

will create a directory C<local> on the host, and then export
the contents of C</remote> on the mounted filesystem to
C<local/remote-data.tar.gz>.  (See C<tgz-out>).

=head1 PIPES

Use C<command E<lt>spaceE<gt> | command> to pipe the output of the
first command (a guestfish command) to the second command (any host
command).  For example:

 cat /etc/passwd | awk -F: '$3 == 0 { print }'

(where C<cat> is the guestfish cat command, but C<awk> is the host awk
program).  The above command would list all accounts in the guest
filesystem which have UID 0, ie. root accounts including backdoors.
Other examples:

 hexdump /bin/ls | head
 list-devices | tail -1

The space before the pipe symbol is required, any space after the pipe
symbol is optional.  Everything after the pipe symbol is just passed
straight to the host shell, so it can contain redirections, globs and
anything else that makes sense on the host side.

To use a literal argument which begins with a pipe symbol, you have
to quote it, eg:

 echo "|"

=head1 HOME DIRECTORIES

If a parameter starts with the character C<~> then the tilde may be
expanded as a home directory path (either C<~> for the current user's
home directory, or C<~user> for another user).

Note that home directory expansion happens for users known I<on the
host>, not in the guest filesystem.

To use a literal argument which begins with a tilde, you have to quote
it, eg:

 echo "~"

=head1 WINDOWS PATHS

If a path is prefixed with C<win:> then you can use Windows-style
paths (with some limitations).  The following commands are equivalent:

 file /WINDOWS/system32/config/system.LOG

 file win:/windows/system32/config/system.log

 file win:\windows\system32\config\system.log

 file WIN:C:\Windows\SYSTEM32\conFIG\SYSTEM.LOG

This syntax implicitly calls C<case-sensitive-path> (q.v.) so it also
handles case insensitivity like Windows would.  This only works in
argument positions that expect a path.

=head1 EXIT ON ERROR BEHAVIOUR

By default, guestfish will ignore any errors when in interactive mode
(ie. taking commands from a human over a tty), and will exit on the
first error in non-interactive mode (scripts, commands given on the
command line).

If you prefix a command with a I<-> character, then that command will
not cause guestfish to exit, even if that (one) command returns an
error.

=head1 REMOTE CONTROL GUESTFISH OVER A SOCKET

Guestfish can be remote-controlled over a socket.  This is useful
particularly in shell scripts where you want to make several different
changes to a filesystem, but you don't want the overhead of starting
up a guestfish process each time.

Start a guestfish server process using:

 eval `guestfish --listen`

and then send it commands by doing:

 guestfish --remote cmd [...]

To cause the server to exit, send it the exit command:

 guestfish --remote exit

Note that the server will normally exit if there is an error in a
command.  You can change this in the usual way.  See section I<EXIT ON
ERROR BEHAVIOUR>.

=head2 CONTROLLING MULTIPLE GUESTFISH PROCESSES

The C<eval> statement sets the environment variable C<$GUESTFISH_PID>,
which is how the C<--remote> option knows where to send the commands.
You can have several guestfish listener processes running using:

 eval `guestfish --listen`
 pid1=$GUESTFISH_PID
 eval `guestfish --listen`
 pid2=$GUESTFISH_PID
 ...
 guestfish --remote=$pid1 cmd
 guestfish --remote=$pid2 cmd

=head2 REMOTE CONTROL DETAILS

Remote control happens over a Unix domain socket called
C</tmp/.guestfish-$UID/socket-$PID>, where C<$UID> is the effective
user ID of the process, and C<$PID> is the process ID of the server.

Guestfish client and server versions must match exactly.

=head1 GUESTFISH COMMANDS

The commands in this section are guestfish convenience commands, in
other words, they are not part of the L<guestfs(3)> API.

=head2 alloc | allocate

 alloc filename size

This creates an empty (zeroed) file of the given size, and then adds
so it can be further examined.

For more advanced image creation, see L<qemu-img(1)> utility.

Size can be specified (where C<nn> means a number):

=over 4

=item C<nn> or C<nn>K or C<nn>KB

number of kilobytes, eg: C<1440> = standard 3.5in floppy

=item C<nn>M or C<nn>MB

number of megabytes

=item C<nn>G or C<nn>GB

number of gigabytes

=item C<nn>T or C<nn>TB

number of terabytes

=item C<nn>P or C<nn>PB

number of petabytes

=item C<nn>E or C<nn>EB

number of exabytes

=item C<nn>sects

number of 512 byte sectors

=back

=head2 echo

 echo [params ...]

This echos the parameters to the terminal.

=head2 edit | vi | emacs

 edit filename

This is used to edit a file.  It downloads the file, edits it
locally using your editor, then uploads the result.

The editor is C<$EDITOR>.  However if you use the alternate
commands C<vi> or C<emacs> you will get those corresponding
editors.

NOTE: This will not work reliably for large files
(> 2 MB) or binary files containing \0 bytes.

=head2 glob

 glob command args...

Expand wildcards in any paths in the args list, and run C<command>
repeatedly on each matching path.

See section WILDCARDS AND GLOBBING.

=head2 help

 help
 help cmd

Without any parameter, this lists all commands.  With a C<cmd>
parameter, this displays detailed help for a command.

=head2 lcd

 lcd directory

Change the local directory, ie. the current directory of guestfish
itself.

Note that C<!cd> won't do what you might expect.

=head2 more | less

 more filename

 less filename

This is used to view a file.

The default viewer is C<$PAGER>.  However if you use the alternate
command C<less> you will get the C<less> command specifically.

NOTE: This will not work reliably for large files
(> 2 MB) or binary files containing \0 bytes.

=head2 quit | exit

This exits guestfish.  You can also use C<^D> key.

=head2 reopen

 reopen

Close and reopen the libguestfs handle.  It is not necessary to use
this normally, because the handle is closed properly when guestfish
exits.  However this is occasionally useful for testing.

=head2 sparse

 sparse filename size

This creates an empty sparse file of the given size, and then adds
so it can be further examined.

In all respects it works the same as the C<alloc> command, except that
the image file is allocated sparsely, which means that disk blocks are
not assigned to the file until they are needed.  Sparse disk files
only use space when written to, but they are slower and there is a
danger you could run out of real disk space during a write operation.

For more advanced image creation, see L<qemu-img(1)> utility.

Size can be specified (where C<nn> means a number):

=over 4

=item C<nn> or C<nn>K or C<nn>KB

number of kilobytes, eg: C<1440> = standard 3.5in floppy

=item C<nn>M or C<nn>MB

number of megabytes

=item C<nn>G or C<nn>GB

number of gigabytes

=item C<nn>T or C<nn>TB

number of terabytes

=item C<nn>P or C<nn>PB

number of petabytes

=item C<nn>E or C<nn>EB

number of exabytes

=item C<nn>sects

number of 512 byte sectors

=back

=head2 time

 time command args...

Run the command as usual, but print the elapsed time afterwards.  This
can be useful for benchmarking operations.

=head1 COMMANDS

@ACTIONS@

=head1 ENVIRONMENT VARIABLES

=over 4

=item EDITOR

The C<edit> command uses C<$EDITOR> as the editor.  If not
set, it uses C<vi>.

=item GUESTFISH_PID

Used with the I<--remote> option to specify the remote guestfish
process to control.  See section I<REMOTE CONTROL GUESTFISH OVER A
SOCKET>.

=item HOME

If compiled with GNU readline support, then the command history
is saved in C<$HOME/.guestfish>

=item LIBGUESTFS_APPEND

Pass additional options to the guest kernel.

=item LIBGUESTFS_DEBUG

Set C<LIBGUESTFS_DEBUG=1> to enable verbose messages.  This has the
same effect as using the B<-v> option.

=item LIBGUESTFS_MEMSIZE

Set the memory allocated to the qemu process, in megabytes.  For
example:

 LIBGUESTFS_MEMSIZE=700

=item LIBGUESTFS_PATH

Set the path that guestfish uses to search for kernel and initrd.img.
See the discussion of paths in L<guestfs(3)>.

=item LIBGUESTFS_QEMU

Set the default qemu binary that libguestfs uses.  If not set, then
the qemu which was found at compile time by the configure script is
used.

=item LIBGUESTFS_TRACE

Set C<LIBGUESTFS_TRACE=1> to enable command traces.

=item PAGER

The C<more> command uses C<$PAGER> as the pager.  If not
set, it uses C<more>.

=item TMPDIR

Location of temporary directory, defaults to C</tmp>.

If libguestfs was compiled to use the supermin appliance then each
handle will require rather a large amount of space in this directory
for short periods of time (~ 80 MB).  You can use C<$TMPDIR> to
configure another directory to use in case C</tmp> is not large
enough.

=back

=head1 EXIT CODE

guestfish returns I<0> if the commands completed without error, or
I<1> if there was an error.

=head1 SEE ALSO

L<guestfs(3)>,
L<http://libguestfs.org/>,
L<virt-cat(1)>,
L<virt-edit(1)>,
L<virt-list-filesystems(1)>,
L<virt-ls(1)>,
L<virt-rescue(1)>,
L<virt-tar(1)>.

=head1 AUTHORS

Richard W.M. Jones (C<rjones at redhat dot com>)

=head1 COPYRIGHT

Copyright (C) 2009 Red Hat Inc.
L<http://libguestfs.org/>

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., 675 Mass Ave, Cambridge, MA 02139, USA.